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Full text of "73 Magazine (January 1972)"


January 1972 
$1 



magazine 

for radio amateurs 



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*73 Tests: Allied AX-190, Simpson Model A f 
IC-21, Regency Transcan, CT Power Amplifier 








2M Antenna 
RTTY Art 
SSTV 

News 

IC Projects 








Perils of Skirting Ma Bell 

Novice 

Morse Code Controversy 

Only a bare hint of FM 
& More 





SSTV 





BEGINS 

1972 



$495 Robot SSTV monitor & free 
personalized SSTV tape* equips 
any licensed ham to enter. 



Sponsored by CQ Elettronica Magazine, 
the contest is open to all licensed ama- 
teurs qualified to operate SSTV. Details 
are listed elsewhere in this magazine, 
*By taking advantage of our current offer 
of a free personalized SSTV tape with the 
purchase of a Robot Model 70 monitor 
(as described in our last month's ad), you 
will have a video SSTV signal you can 
transmit without having to own a SSTV 
camera. 
So for the price of the Robot monitor 



alone ($495) you will have all the equip- 
ment necessary to enter the second 

WORLD WIDE SSTV CONTEST! 



ROBOT MODEL 70 MONITOR 
ROBOT MODEL 80 CAMERA 
25mm f 1.9 lens 



* « -> 



....$495 

$465 

$ 30 



FOR A FREE BROCHURE ON SSTV AND THE 
ROBOT CAMERA AND MONITOR WRITE 



[robot] 

7591 CONVOY COURT, SAN DIEGO, CA 92111 (714) 279-9430 



See the complete line of Robot SSTV equipment at your local Robot dealer listed below. 

Birmingham, Ala. 35233, James W. Clary Company,* 1713 Second Avenue South, (205) 322-2486 * Anaheim, Calif. 92804, 
Henry Radio Company, 931 North Euclid. {714} 772-9200 • Los Angeles, Calif. 90064, Henry Radio Company, 11240 West 
Olympic Boulevard, <2f 3) 272-0861 • Oakland, Calir 94607, Amrad Supply, 1025 Harrison Street, {415) 451-7755 • Denver, 
Colo. 30202, CW Electronic Systems, 1401 Blake Street, (303} 244-5523 • Miami, Ra, 33137, Amateur Radio Center, Inc., 
2505 NE Second Avenue, {305) 374-4101 • Honolulu, Hawaii 96803, Honolulu Electronics, 819 Keeaumoku Street, (808} 
949-5564 • Reading, Mass. 01867, Graham Radfo Company, 505 Main Street, (617) 944-4000 • Muskegon, Mich. 49441, 
Electronic Distributors, Inc., 1960 Peck Street, (616) 766-3196 • St Louis, Mo., 63132, Ham Radio Center, 8342 Olive 
Boulevard, (314) 993-6060 • Amsterdam, N,Y. 12010, Adirondack Radio Supply, 185-191 W, Main Street, (515) 842-8350 

• New York. N.Y. 10012, Barry Electronics, 512 Broadway, (212) 925-7000 • Ashevllle, North Carolina 28801, Freck Radio 
Supply, 38 Bittmore Avenue, {704) 254-9551 • Cleveland, Ohio 44112, Amateur Electronic Supply, 17929 Euclid Avenue, 
(2T6) 486-7330 • Dayton, Ohio 45404, SREPCO, 314 Leo Street. {513) 224-0971 • Trevose, Pa, 19047, Hamtronlca, 4033 
Brownsville Road, (215) 357-1400 » Fort Worth, Texas 76110, Ed Juge Electronics, 3850 South Freeway, (817) 926-5221 

• Spokane, Wash, 99206, HCJ Electronics, E, 8214 Sprague. (509) 924-2343 * Milwaukee, Wise. 53216, Amateur Electronic 
Supply, 4828 W, Fond du Lac Avenue, (414) 442-4200 * CANADA: Fredericlon, N. B., Audio Lectronics Ltd., 79 Prospect 
Street, (506) 454-3380 • Downsvllle, Ontario, VE Amateur Radio, 3768 Bathurst Street. {416) 636-3636 * Montreal, Quebec, 
Payette Radio Company, 730 Si. Jacques, (514) 866^6681. 




magazine 

for radio amateurs 



#136 JANUARY 1972 



WA6PIR 



FEATURES 

2 Radio Amateur Newspage 

3 Repeater Update 

4 Never Say Die W2NSD/1 

6 Guest Editorial W8GI 

7 New Products 
9 Novice 

9 Letters 

12 Caveat Emptor 

12 DX Footnotes 

44 Let's Revise the Morse Code 

96 Propagation 

96 Advertiser Index 



Editor-Publisher 

Wayne Green W2NSD/1 
Associate Editors 

Jim KyleW5JKX 

Natalie RudWB2PQZ 
Assistant publisher 

Phil Price 
Assistant Editor 

Eric Falkof K1NUN 
WTW Editor 

Dave Mann K2AGZ 
Advertising Manager 

Aline Coutu 
Art Director 

Roger Block 
Graphics 

Nancy Estle 
Composition 

Ruthrnary Davis 
Subscriptions 

Dorothy Gibson 
Circulation 

Barbara Block 
Comptroller 

Georgianna Sage 
Publications 

Biff Mahoney 
Traffic 

Taylor Sage 
Maintenance 

Brad Winters 

Annette Vincent 



CONTENTS 

13 RTTY Art ... , 

A new art form is born. 
17 The TT-63A As A Display Generator . , , . .K2BEH 

Surplus conversion for RTTY. 
21 Television Monitor .„...., m f . K0MOC 

All solid-state except for the tubes. 
27 73 Tests The Icom IC-21 Transceiver K1 NUN 

Twenty-four channels — holy moly! 

29 73 Tests the Regency Transcan FIW Transceiver ...... W2NSD 

Listening to S repeater channels at once, 

30 73 Reviews The Allied AX-190 Ham Receiver Staff 

New solid state receiver for $250 

31 Phone Phreaks vs Ma Bell , WB8LBV 

How people get caught cheating TPC. 
35 AFSK Revisited WA3AJR 

or, How I learned to stop worrying and love teletype. 
39 Tuning Indicators for SSTV Monitors K7YZZ 

The sooner you try SSTV the better for you. 
45 Designing Diode Matrix Units WA0ZHT 

For automatic ID. 
53 Circuits, Circuits, Circuits , Staff 

Circuits. 
57 The Making Of A Modern Day Receiver W2FEZ 

Why some are better than others. 
61 Simultaneous Multi-Band Transmissions , . W2EEY 

In case you want to imitate W1 AW. 
67 A Pre-Novice Transmitter WASOIK 

A fun way to learn code. 
69 The Problem of Inversions K3WNX 

The logic of USB vs LSB on SSB. 
73 A Medium Frequency Converter For High Frequency 

Receivers. VK3IQ 

Tuning 400—1000 kHz on your 80m receiver. 
75 Easy End-Feed Z Match G30GR 

End-feed antenna 80— 10m. 
77 Coat-Hanger Antenna For 2 Meters Revisted . 

The improved coat-hanger. 
79 73 Uses The Simpson Model A 

Well designed, well built. 
85 73 Reviews the CT Power Amplifiers 

Tiny mobile rock crusher. 
87 Optimal Vertical Antenna Loading Techniques 

A vertical can be satisfying. 



Gelsinger 



Staff 



Staff 



W2EEY 



73 Magazine is published monthly by 73 Inc., Peterborough, New 
Hampshire 03458. Subscription rates are $6 for one year in North 
America and U.S. Zip Code areas overseas. $7 per year elsewhere. 
Two years $11 in U.S. and $12 overseas. Three years $15, and $16 
overseas. Second class postage paid at Peterborough, N.H. and at 
additional mailing offices. Printed at Menasha, Wisconsin 54952 
U.S.A* Entire contents copyright 1971 by 73 Inc., Peterborough, 
N\tL 03458. Phone: 603-924-3873. This issue is a bit thinner than 
we like, but if you check you'll see that we still have a whole lot 
more pages of articles than our competition who has seen fit to try 
and start a price war. . . a war that can only result in fewer and 
fewer articles being published by all ham magazines. Think of that 
the next time you buy brand Y. Better that 73 be a bit thinner and 
be healthy than thick and going broke. Now turn to the readers 
service coupon on the last page and send it i>2. 



JANUARY 1972 



1 



Amateur Eabto 



JANUARY MCMLXXII 



Monthly H 



FAMILY HELPED 

BY AMATEURS 

SON STRICKEN IN GERMANY 



(Re printed from tt?e Wfflknmport 
Sun-Gazette) Mr. and Mrs. William J. 
Shannon recently learned that kind- 
ness can extend for thousands of miles. 

On Sept. 1 . the Shannons got a 
cable from their son, John, saying he 
was ill in Heidelberg Polyclinic Hospi- 
tal. Heidelberg, Germany. He had 
been on vacation in Europe, He is 
head of the music dept. at Wyoming 
Seminary, near Wilkes-Barre. 

Mrs. Shannon called the hospital, 
but was told that no John Shannon 
was listed. 

"We were really worried/' recalled 
Mrs. Shannon. "John wouldn't have 
cabled unless he was seriously ilk" 

The Shannons tried to contact their 
son by cablegram but with no success. 

Finally they went to the Red Cross, 
but that attempt also failed. The Red 
Cross suggested however, that Mr. and 
Mrs. Shannon try to contact Germany 
by ham radio. 

Mrs. Shannon's brother, Robert 
Stout W3NEN. put them in touch 
with Donell Godfrey K3QFW, the 
past president of the West Branch 
Amateur Radio Club. 

4 'Mr. Godfrey is the hero of this 
story," said Mrs, Shannon/' He's the 
one who helped us get into contact 
with someone who knew about our 
son/' 



On his radio, Don contacted 
Guenther Herzog in Hemer, Germany, 
about 250 miles from Heidelberg. 

Fortunately, Herzog had a friend 
who was on the staff at the Heidelberg 
Hospital. Herzog learned that John 
Shannon was indeed in the hospital 
and seriously ill with a strange type of 
virus. 

"They aren't sure what type of 
virus John has," his mother con- 
tinued, "but one doctor in Austria 
said he could have gotten it from 
eating bad meat or ice cream/' 

Herzog offered his home to John 
when he leaves the hospital if he needs 
rest before returning home. 

The Shannon's eldest daughter, 
Carol, an airline stewardess, flew to 
Germany to see her brother. "The 
doctors said that seeing her was the 
best medicine," the mother said. 

Carol called her parents last night 
and told them John was much better. 
She plans to bring him home soon. It 
will probably be a while, however, 
until he returns to teaching. 

Mrs. Shannon was much relieved 
today after the trying experience. "It 
seems like a small world," she said, 
"'when people like Mr. Godfrey and 
Mr + Herzog will go out of their way to 
help you." 



JOHN GORE SCHOLARSHIP AWARDED 



Alan Scott WB2TCZ, of Paint Post. 
New York, was this year's recipient of 
the John Gore Memorial Scholarship. 
Judged to be the most scholarly and 
deserving of applicants nationwide, on 
September 23rd. Scott was awarded 
the 5500 scholarship, John Gore was 
an outstanding past president of t Ik- 
Foundation for Amateur Radio, a 
group of twenty-seven radio clubs in 
the Washington, DC\ urea. 



Alan Scott is an electrical engineer- 
ing student at the University of Cin- 
cinnati, has been on the Dean's list 
several times, and participates in a 
co-op program with the Naval Re- 
search and Development Center in 
Carderock, Md. 

Information about this scholarship 
will be available in 73 in a few 
months. 



Swiss Scouts 
In JAMBOREE 




Recent participants in the Jambo- 
ree On The Air held in October. 




Leie HB C >AMY, in the San Gottardo, 
Lugano -Tl- Scout Section, allows 
local scouts to talk with other scouts 
in other parts of the world. 



Contest Announced 

The Potomac Area VHF Society 
Challenge Competition consists of a 
contest with any club that dares to 
compete in the January VHF Sweep- 
stakes. Take your club aggregate 
score, divide by number of members, 
multiply by percentage of members 
participating. Clubs must have six or 
more members and have been in exis- 
tence since 1/1/71. At least fifty per 
cent of the members must have been 
in the club before 7/1/7L Honor 
system will be used in computing 
scores. Highest scoring club by this 
system, other than PAVHFS. will re- 
ceive an engraved trophy. Any club 
scoring higher than contest sponsor 
will receive a handsome certificate. All 
mail handled by K3LNZ. 



J5eto£ 




ews of the World 



73 MAGAZINE 



IN WORCESTER, MASSACHUSETTS: 



FM SYMPOSIUM FEB. 12 



th 



A lull-fledged hassle and exposition 
is in Ihe works for mid-February in 
the Worcester (Mass.) area. If you 
have any interest in FM. two meters, 

IT ■ 

ham fist-fights, looks at the newest 
developments In ham gear, and such, 
you might consider braving the wintry 
winds of central Massachusetts and 
heading for a full day of enervation at 
the First New England FM Sympo- 
sium. 

The need for some sort of general 
eonilab of the 40-plus repeater groiij 
in New England reached the level 
where even 73, which has taken little 
note of this new-fangled flash-in -the- 
pan FM lad, felt constrained to follow 
the lead of its publishing compatriots 
and make a fast buck while the 
pickings are thick. 

The Symposium will attempt to get 
the 40 groups face ro face in the hope 
that a frequency coordinating board 
can be named to plot the progress of 
repeater allocations in New England. 
Arguments will be heard on closed vs 
open repeaters, television and RTTY 
repeaters, touchtone vs tone burs I 
entry and control, big vs little repeat; 



ers, repeater tie-ins, and plans will be 
discussed for expanding repeater op- 
erations to other bands such as 75m, 
40m, 20m. 10m, 6ni, and even 220 
and up! 

Watch the February issue of 73 for 
final details on place and program. 
The program will start at 10 am and 
1 : j ^ t through until late that night. 
lalk-in will be through any of the 
dozen or so nearby repeaters or on 94 
direct. Listen 19*79 W \]RGO 37-97 
WA1KRJ. 25-76 KIMNS, 34 94 
K1AIU. 34 94 WA1KGR. 
WAIKGZ. 22 82 WlHWk, 
K1AOI, 01-64 WAIKGS, 
KIFFK. 10-70WAIK1/ etc. 



25-79 

28-88 
04-91 



NEW FREQUENCY SYNTHESIZER 
IN THE WORKS 

Vanguard Labs is hard at work on 
their frequency synthesizer for FM 
and you should see announcements 
soon for a transmitter model with 
output on 6, 12 and 18 MHz for two 
meter transceivers and hitting every 
10 kHz for around S 1 00. This one will 
operate over a ±I0°C temperature 
range. Andre will have one for 10 to 
+70° C for around SI 50. 



^REPEATER UPDATE 

LISTENING 

94 76 88 73 70 64 82; ... 



NY WA2PDJ 

M WAZUZE 

NY UJIttJS 

OH »A*WMH 

OK WA5VL H 



■ 



AZ K7ZMA/7 

I A WAr.i HZ 

to WA0SNO 

(I WAlRQfi 

IL WH'JIIWS 



IN K9JSI 

IN W'K.'FJ 

MA k l Ml 

M \ ft MM Q 

MA \v\imh\ 

Ml WIQXR 
MD OBI 
VfD WAJPVP 



Ml «b«(Kk 

Ml WSMAI 
MS 

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Mdk. 






Hydcn fttak, Huulpia Mtn 34 ( M 
I0D\ nr Kingman AZ 

I ■ •■ A ii«vli*s 145 J 5 



Pnt*hJo 



34 

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04 



FanningtdJl 

Chun go ftohi 22-70 to: 

:(}{!() 11/ tone 

ffnmgp QTH to Western Springs 



4'i 

MS 

fi-4 



OR 

PV U^H\ 

PA *-iOl 

PA WA3QCE 

PA kUTQD 

p* ^A.iwjtr? 

S( WU4QGK 

WA WA7KGV 

W\ VAYR 



{ lunec from 52 76 it> 

|4f-445 147 ^r, 
Hunt met nn 52-76 

BjyvJr 4i h4 

Bulli-r * 37 97 

DiiFjnl 34-^4 

kmg Mm 34 «M 

Mary's Pojk 34 "4 

Oiangi? from 52,525 M0 lo 

52 575-1*80 
AlU-nfown 34 tJ 4 

Pimbiitg lugginje info ^4 R6 

1"ir>l 15 igt Isl lunvmi^ion 
Delete I rum \w\ 

Sainton 34 l m 

OurlrclKii M 4 M 

Bawfan 34 *M 

1,95 kHz tOfW hurst 

Green Bjv 2S 8H 



LuPork 

Midii^m City 
I KinungEiLirn 

mervUle 
Bangor 

t !itvs,-rl> 

Motion 

Benton Harbor 

DulutJi 

Petcrbcm 

iters 4 



22 x: 

31 97 
34 "4 
07 67 

14 ''4 

ai 61 
ii.i 30 22430 

44*. 3 44*1 
44" 444 rj 
22 - 

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API ! «M 



Thanks to WA9SXN. WB9HWS. 
K L >DZF, WA9AFM/0, KHZOA. 
K7ZMA, K5BNK. W3WK\ K3BEQ, 
K2VWZ, WIKJL. WKiBQ, W1BHD. 
W1AGJ 

Please, when reporting repeater ac- 
tivity, give call letters and location. 
Club bulletins often omit these items 
but we need it to adequately inform 
our readers. 

Tone-burst Freq\ 1.5* 1.65, 1.8, 
1.75. 2.1, 225. and 2.4 kHz. 



MASSACHUSETTS 
HAM WINS 
COMMUNITY 

SERVICE AWARD 

73 salutes WINN of Reading, Mass., 
who, according to the Reading Chron- 
icle, is the recipient of the radio 
station WEZh Community Service 
Award. I heodore Barron, an active 
phone-pat cher. earned the award for 
helping people in need throughout the 
Western Hemisphere. In recognition of 
this feat, we congratulate you for 
typihing the ham radio operator as 
dedicated lo public service. 



HOT GEAR 

House ot K2AOQ, Melvin Sloller. 
373 Park Ave,, Rochester. NY, 
(71 6-244-2839) burglarized Sept. 26. 
New GE Personal Portable Master Ra- 
dio, model PR"36~RFS-55, S/N 
1041218. Set up for 28/Sa, 94/94, 
34/94, 34/76. Reward for info lending 
to recovery. Contact Mel or Rochester 
Police, Detective Division. 

S-Line stolen from Colorado State 
Univ. during summer, 75S3-B S/N 
15M0: 32S3 SN 12000: 5J6F2 S/N 
1649, all have distinguishing marks. 
Contact W, Solfermosen ! c >05 W. 
Lake. Ft, Collins CO 80521 
(482-9668 \ or Dave Balsick. 515 S. 
Meldrum, Ft. Collins CO 80521 
(493-4774). 

STOLEN: Simpson Electronics Mod- 
el- A FM transceiver (serial number 
35457) and a Hy-Gain Diploma t-2 5/8 

wavelength mobile whip with magnet- 
ic base, de W2PWG. Robert F. Scott, 
9 Jackson Avenue. Brentwood NY 
11717. 



HOT GEAR CUMULATIVE 

Mf r r| Model, Ser, No, 

HjIIi . NR4fiA, ~44f*tUIJ 
Reg MR : 904-03505 
S <ri;ti\ FM360L^1003 
Coll .. 75A4. #804 
U-., Portable. =104 1 : 18 

II, 75St-B, =15640 
CotL.2IS3; #12000 
Coll . 516F2 t #l649 
Swan. 350. #C5<S7347 
Hiimm. HXL-L#33M1269 
Wos,; TA-/ 



LISTING 
Owner 
WAlhMLf 
WA5HNM 

wb:arm 

W9MGI 

k:aoq 

CoLStl 

Col.SlU- 

ColSfU. 

W^SIB 
KZ5MM 
KZ5MM 
KZ5MM 



Issue 

9/71 
11/71 
II 71 
I 2/71 

I 12 
I 72 

I 72 
I ^2 



mm 




Ten Meter FM Link 

A call from W7DXX got the juices 
boiling for a ten meter link channel 
between FM repeaters around the 
country, or even around the world. As 
a result I have ordered a little ten 
meter FM rig which we will be setting 
up in conjunction with WAIKGO to 
send and receive on 29,68 MHz with 
tone access from the 19-79 two 
meter service. 

When six meters opens up I have a 
great time through W1ALE in Con- 
cord, N.R, which has a 52.525 MHz 
function connected to its 46-94 oper- 
ation. Ten should be even more fun 
since it opens a lot more than six 
does. 

Say, Til bet all those swingers down 
on 3999 kHz would really dig a link 
to that channel through your repeat- 
er! How about it? It would wake 'em 
up for sure. When you do it please be 
sure to make careful notes of the 
ensuing bedlam and send them to 7i 
for the newspages. 

In the meanwhile, how about get- 
ting set up on 1 Om so we can have 
some news of mobiles in Munich 
talking via 2m-IOm repeater to 
Oregon? 

Expanding the Tech Band 

The FCC has been sitting on several 
proposals to expand the Tech frequen- 
cy allocations on two meters. If. for 
some reason which Js really not too 
apparent, the FCC is reluctant to let 
the Techs use ail of 2m, perhaps they 
would buy an expansion of the band. 
This could be tried if an individual or 
group would petition the FCC to 
expand the Tech privileges to, say, 

144.5 through 148 MHz. This would 
still leave 500 kHz for the higher class 
licensees, which is far more than 
adequate for the amount of activity 
on the band at present , , , or that has 
been on the band during the last 20 

yean; ... or that we can envison on 

the band in the foreseeable future 

unless some development comes along 

which is not imagined yet. 

The progress of FM would be eased 

with such an expansion. What do you 

think? 

Ideas 

The Morse Memory unit in the 
December issue got us to thinking, 
when this is used for repeater ID ? all 
that storage capacity is not really 
needed , , , so why not use some of 
the left over IC function for a timing 



EDITORIAL BY WAYNE GREEN 

circuit or two? Most repeaters need a 
timer to permit a one to three second 
lag for the squelch tail and another to 
time the repeater off the air if a 
continuous signal comes in for three 
minutes. 

And how about someone coming 
up with a simple LED numerical 
readout for FM channels which is 
controlled by the crystal switch? You 
wouldn't need a counter, just a means 
of coding the readout when the parti- 
cular crystal is installed. It would be a 
lot better than just channel numbers, 
right? Two numbers for the transmit 
channel and two for the receive would 
do it. Well? 

220 Repeaters 

Little has been done with 220 FM 
as yet and the pattern of repeater 
channelization is in a state of flux. I 
would like to offer the pages of 73 as 
a forum for discussion of possible 
channel plans. As a starter you might 
consult the chart on page 100 of the 
April issue of 73 which listed the 220 
proposed channel frequencies. 

One of the deficiencies of the two 
meter FM development, from my 
point of view, was the use of the 
commercial scheme of using just one 
channel for both transmit and receive, 
thus enforcing the usual type of radio 
contact where one person at a time 
can talk. Duplex, where both parties 
can talk at once, would be more fun 
and, unless there are serious problems 
of available frequencies, would seem 
beneficial. So naturally I suggest that 
we give strong consideration to setting 
up 220 for duplex operation. 

If we set up our repeaters on 220 
spaced 3 MHz. we should be able to 
receive while transmitting without any 
serious problems. Okay for one chan- 
nel. So I propose that we start at 
220.02/223.02 for the first pair, and 
then run a duplex pair for that repeat- 
er on 220.06/223,06. In use we would 
transmit on 220.02 and receive on 
223.06 for one pair and transmit on 
220.06 and receive on 223.02 for the 
second pair, transmitting and receiving 
simultaneously for full duplex opera- 
tion. If 220 repeaters proliferate any- 
thing like 146 repeaters, the crystal 
expense could be almost prohibitive, 
running double that of two meter 
channels. I suspect that synthesizers 
will be with us shortly and will pro- 



vide a low-cost solution to that diffi- 
culty. 

If you have any experience or 
educated opinions on repeater channel 
standards for 220 please consider this 
a request for your expertise. 

Coming Special Issues 

We are hard at work on our usual 
spectacular March Surplus Issue of 73. 
If you have any last minute surplus 
conversions (relatively simple ones) 
this is the time to send them in. And 
what else would you tike to see in a 
surplus issue? Let me know, Til try to 
have the biggest collection of surplus 
ads I can muster, 

April will again be special FM 
Month. I would appreciate getting as 
many FM circuits as possible for 
inclusion in this issue. Please make the 
circuits as complete as possible so 
only a little text is required for them. 
Send in tone code, decode, COR, PL, 
touchtone, control, timers, identifiers, 
logging devices, antennas, or whatever 
you think you might have that others 
would like to know about and have 
not seen. Til have a complete crystal 
selection chart for all commercial rigs 
in the issue. And Til try and bring you 
a complete rundown on all available 
FM harn transceivers, amplifiers, and 
such. 

Beyond April we are working hard 
on special features in later issues on 
portable and mobile equipment, an- 
tennas and towers, VHF/UHF, DX> 
I C/ so lid state ... and plenty etc. 

FM Expansion Proposal 

The FM channels between 
146—147 MHz are pretty well occu- 
pied in the New England area and are 
filling up rapidly in several other 
population centers. The question that 
arises is where next? 

Since there is no FCC regulation 
prohibiting the repeating of a Tech 
licensee into a higher class license 
segment of the bands providing the 
licensee of the repeater is appropri- 
ately licensed, the expansion of re- 
peater outputs into the 147 MHz 
range is possible. But where do we put 
the input? 

In practical application, most of the 
AM and other non-FM activity on two 
meters occupies the lower half MHz of 
the 144 and 145 MHz segments of the 
band. It seems to me that it would be 
practical for FM repeaters to start 
using the other half MHz bands, with 
their input from the 145.5 to 146.0 
band and output in the 144.5-145.0 
band, separated exactly 1 MHz. Re- 
member that the 600 kHz separation 
used in the 146 MHz band was a 
compromise for operators who 
wanted to transmit on both input and 
output frequencies (146,34 and 
146.94) without having to re tune 
their rig. If you can give up the need 



to use tile repeater output as a sim- 
plex channel you are freed from the 
600 kHz restriction. 

If we had it all to do over I just 
wonder if we might not opt for an 
even wider spacing between input and 
output so full duplex would be pos- 
sible? A 2 MHz spacing would permit 
this and enable us to indulge in a 
completely different type of contact, 
WelK I guess it is too late to cry over 
spilt milk on two meters, but we 
certainly should keep this lesson in 
mind when we start populating 220. 

What do you think? 

Proposed FM Repeater Channels 



Input 


Output 


145.50 


144.50 


145.53 


144.53 


145.56 


144.56 


145.59 


144.59 


145.62 


144.62 


145.65 


144.65 


145.68 


144.68 


145.71 


144.71 


145.74 


144.74 


145.77 


144.77 


145.80 


144.80 


145.83 


144.83 


145.86 


144.86 


145.89 


144.89 


145.92 


144.92 


345.95 


144.95 


145.98 


144.98 


FM News 



C. T. Power, who makes the Tempo 
amplifiers being marketed by Henry, 
will be out shortly with a little FM 
two meter amplifier for under $100 
(namely $99.50) which will take the 
average ! watt transmitter and boost 
it to 40 watts out. This should be a 
popular item since an extra 6 dB from 
most mobile rigs could extend the 
range substantially. Their 220 trans- 
ceiver, announced recently, is serious* 
ly back ordered, proving that a U.S, 
made 220 transceiver at $180 was 
definitely needed. Their repeater ver- 
sion of the rig should be along soon 
and we're going to do everything we 
can to encourage every repeater group 
in the country to add a 220 MHz 
repeater to their present setup in the 
hope that a quick population explo- 
sion in that band might tilt the table 
in our favor when it comes to consi- 
deration of the dreaded EI A proposal 
to carve up that band for the CEers. 

As if all that weren't enough, C T. 
Power is also hard at work on a 450 
MHz transceiver. They already have a 
beauty of a solid state 450 amplifier 
which turns 4 watts into 30 watts and 
sells for $210- If they can keep up 
with the commercial demand for that 
one perhaps we will be seeing some on 
our 450 repeaters. They also have a 
two meter transceiver and a repeater 
package well along. The transceiver 
will have 1 1 channels plus a vfo and is 




EVENTS 



GATHERINGS 

Wheaton Community Radio Ama- 
teurs (WCRAJ will hold its tenth 
annual Mid-Winter Swap and Shop on 
Sunday, Feb, 20 at DuPage County 
Fair Grounds, Wheaton, 111.; 8:00 
a.m. — 5:00 p.m. SI advance, SI. 50 at 
door. Refreshments and parking. 
SASE to WCRA, P.O. Box QSL, 
Wheaton IL 60187 for info. 

California 

Southern California DX Club plays 
host to the 23rd annual California DX 
Conference on January 22 and 23 at 
the Del Webb Towne House in Fresno. 
Beginning and experienced DXers are 
invited to attend. Speakers include 
3C0AN, ZA5C, VK9NP, and 3B9DJL 
Talk, cocktail party, steak dinner, DX 
breakfast on Sunday are some of the 
events of the conference, Signal/One 
CX7A pre-registration prize. Send 
check for $14.50 to SCDXC Treas. 
Jack Hollander WB6UDC, 13531 
Malena Dr., Tustin CA 92680. Include 
SASE. Pre-registration ends Jan. 7, 

Indiana 

The Lake County ARC's nineteenth 
annual banquet on February 12 will 
be held at a different location this 
yean It will be at the Scherwood Club 
in Sehereville, Indiana. Map is on back 
of the five dollar tickets which can be 
obtained from Herb Brier W9EGQ, 
Ticket Chairman, 385 Johnson St., 
Gary IN 46402, or from other mem- 
bers. No tickets at door 

Arkansas QSO Party 

From 2200z Sat. Jan 22 to 0400z 
Mon. Jan 24. Ark stations score 1 pt 
per contact times number of States, 
Provinces and countries worked. Non- 
Ark stations 5 pts per Ark contact. 
Stations may be worked once on each 
band and with each mode. Certificates 
for highest scorer in each State, Pro- 
vince and foreign country with 100 
pts or more. Exchange QSO number 
and signal report plus State or coun- 
try. Suggested freqs are 3560, 7060, 
14060, 21060, 28060, 3960, 7260, 
14300, 21360, 28560; 3735, 7175, 
21 1 10. Logs before Feb 21 to North 
Arkansas Amateur Radio Society, Rt 
1, Green Forest, AR 72638, 



planned to sell for about $255! 15 
watts. The repeater will have its own 
1 2 volt supply and use a car battery in 
case commercial power is interrupted, 
with its power supply keeping the 
battery in full charge. 



Contests 

Second World SSTV Contest, spon- 
sored by cq elettronica magazine. This 
contest is to promote increased inter- 
est in SSTV as used by radio ama- 
teurs. Contest period is Feb, 5, 1972, 
1500-2200Z, and Feb, \% 
0700-14002. All bands may be used, 
and the exchange is picture and num- 
ber of the message, 

Two-way contacts score one point 
(total points is number of individual 
stations contacted), no extra points 
for contacting same station on differ- 
ent bands. There is a multiplier of 10 
points per continent and 5 points per 
country (ARRL list). Score is com- 
puted by multiplying exchange points 
times multipliers. AH logs to be sub- 
mitted must contain date, time 
(GMT), band, call, message numbers 
sent and received, and points. 

Send logs to Prof. Franco Fanti, via 
A, Dallolio 19, 40139, Bologna, Italy, 
First prize is a year's subscription to 
cq ellettronica; second and third 
prizes are 6 month subscriptions. 
There is a special SWL prize, 

The Milliwatt; National Journal of 
QRPP once again will sponsor a QRPP 
NET for 1971-72, commencing opera- 
tion on November 15, 1971. The 
QRPP NET will utilize the QRP ARC 
I calling frequencies of 7040 kHz and 
14065 kHz, Regular NET times are: 
7040 kHz - 0830 EST Wednesday; 
14065 kHz - 1 100 EST Saturday and 
1800 EST Sunday. Procedure: check- 
ins will call CQ QRPP NET and make 
contacts individually ; there will be no 
regular NCS, as we will allow condi- 
tions and activity to determine opera- 
tion of the NET. In addition to the 
regular NET times, stations are re- 
quested to monitor the NET frequen- 
cies for possible calls at the following 
times: 7040 kHz - Sunday, Monday 
and Wednesday at 2100, 2200, and 
2300 EST; 3 4065 - Sunday, Tuesday, 
and Thursday at 0900 and 1845 EST. 
Monitoring stations are requested to 
tune ±2 kHz, and should be reminded 
that calling stations, running at the 
milliwatt power level, will probably be 
weak, and hence rf gains should be 
turned up. We request stations making 
contact on the NET to report them to 
The Milliwatt c/o Adrian Weiss, 117 
Central St. #F-10, Acton MA 01720. 

Also t The Milliwatt sponsors two 
awards for QRP DX operation. One is 
for low power contact with twenty- 
five or more countries, and the other 
is for very low power (under 1W) 
contacts. For full details, contact 
Adrian Weiss at the above address and 
include a SASE, or check a copy of 
The Milliwatt 



Guest Editorial 

Weils Chopin WSGf 

The introduction to the fiftieth 
anniversary publication of the Insti- 
tute of Radio Engineers proceedings 
started thusty: "The life of a man or 
organization has been aptlx compared 
to the sequence of lights and shades 
during one day on earth- In the early 
morning, long shadows lie to the West 
as the sun rises. Then these shadows 
shorten as the day advances until no 
shadows are visible in the noonday 
blaze of light. And later, the shadows 
lengthen as the sunlight wanes, and 
twilight and night approach.' 1 

These words were written during a 
critical period of the life of two very 
fine professional organizations, the 
Institute of Radio Engineers (IRE) 
and i he American Institute of Electri- 
cal 1-ngineers (AIEE), Both organiza- 
tions were facing real problems and 
both competed in many instances for 
the same men. The managers of these 
groups being professional men — 
recognized the dynamic changes 
swarming around them and planned 
ahead. They could see that both 
groups were headed for trouble unless 
something was done. They acted, 
merged, and formed the present Insti- 
tute of Electrical Electronics Engi- 
neers (IEEE), which is now a very 
fine, respected and prosperous organi- 
zation. 

Herein lies a parallel the ARRL 
is in the shadows of the afternoon and 
faces the darkness of the night, and 
the same type of problems that the 
IRE AIEE faced. It is amazing to look 
at the parallels. In amateur radio we 
have CW vs phone. DX vs ragehewers. 
traffic men vs non-traffic men. one 
band vs the other, one modulation vs 
the other, miscellaneous organizations 
jnd their separate goals, ad inllnitum. 
Yet all these men are amateurs and 
should be brothers. Just as the IRE 
and AIEE did. the ARRL faces many 
of the same type of problems, includ- 
ing financial difficulties. So what do 
we do about it? 

It is interesting to compare the 
problems of IRE and AIEE to those 
of the League and at the same time 
look at the different approach to their 
solution. First of all. the IRE put their 
problems on the table. They were 
freely admitted and written up in the 
Proceedings, both pro and con. The 
Proceedings did a magnificent job of 
defining the problem, presenting both 
sides. They did a real management job 
and followed this up with action and a 
factual reporting job. When a merger 
was suggested, they presented the pros 
and cons and sold the idea ITia t is 
why the IEEE is a solid, respected 
organization. They knew how to keep 



their members happy; they calmed 
distention through the printed word. 
Why not take a serious look at the 
IEEE and take advantage of their 
experience in successfully solving the 
same sort of problems we amateurs 
face. 

The IEEE now has two maeazine^ 
for its members. One is very technical. 
the other is more broad brush and 
appeals to those who do not care for 
the highly technical. They have 34 
technical groups, each with a different 
interest, and each have local chapter 
meetings. Each group has a small 
paper-type of publication for its mem- 
bers which covers their particular in- 
terests. The IEEE has regional and 
local chapters. According to a 1 c >70 
article in their Spectrum magazine, 
the IEEE has 169,059 members, not 
unlike that o( the League numbers or 
at least what the League numbers 
should be. They have different classes 
of memberships, including Fellow 
Senior Members. Members, and Stu- 
dent Members, 

The roster of the IEEE has thou- 
sands of amateurs. One famous, highh 
respected name that appears in the 
roster is thai of our former ARRL 
president. Mr. George Bailey. In the 
past the ARRL has had some wonder- 
ful, highly respected, very competent 
men as president for instance, 
Herbert Hoover. Jr. Now let's ask why 
these men resigned the presidency of 
the ARRL? All you have to do is read 
the Constitution and by-laws to find 
the answer. As you read, you find that 
the president is for all intents and 
purposes, powerless to act. Therein 
lies a basic problem. Therefore let's 
take a look at our antiquated Consti- 
tution and by-laws and bring them in 
tune with the times and give our 
president some real authority and 
responsihilits . Lef s have a paid presi- 
dent who works at the job. Other 
sections o( the Constitution eliminate 
some real talent, because they pro- 
hibit a person to be a director who has 
an interest in manufacturing of elec- 
tronic equipment, or a person associ- 
ated with a radio magazine. There are 
other sections just as unwieldy and 
outmoded as these. How about a 
committee to report on bringing our 
Constitution and by-laws in Tune with 
the times? 

Let's look at a name change to 
better reflect the purpose we have of 
selling amateur radio. Then pattern 
local chapters of amateur radio groups 
just like the IEEE. For instance, why 
not call our League the Institute pi 
Amateur Radio, and then instead of a 
flock of clubs with various names and 
amis we could have, for instance, the 
Detroit Chapter of the Institute of 
Amateur Radio, and under that sub- 
head have the Detroit DX group ol 
the IOAR. the Two Meter group and 



FM, the CW group, and so forth, and 
then have Michigan Regional Stale 
groups Here in Detroit we have a 
social occasion each year for the 
regional IEEE members. Why not en- 
vision all amateur radio groups under 
one name? A name projects one*s aim 
or purpose. Who knows what the 
ARRL means but an ARRL member? 
Let's get public relations conscious 
and organization conscious. Look at 
the power of the auto workers and the 
various other unions. In union there is 
strength! 

Now let's take at look at the 
League. Only one side of the story 
appears in QST and that is highly 
biased. You never read what a director 
stands for. Even our directors cannot 
get the other side of the picture 
printed. Why can't the ARRL lay the 
problems on the table and then solve 
them and sell the solution to all - 
repeat, all - amateurs and not just 
League members, and at the same 
time show the importance of all ama- 
teurs belonging to the League, It just 
is nor healthy to have dissension in 
the ranks of the ARRL dividing the 
approximately 80,000 members. At 
the same time, we tell 200,000 other 
non-member amateurs what is good 
for them, and we supposedly repre- 
sent their views in the League presen- 
tations to the FCC, when in fact they 
haven't been represented at all and 
what's worse - they don't know what 
is going on because they don't get 
QST and don't even have the chance 
h> read the biased views presented. 

Why do we resist change? Those 
who resist change generalK suffer the 
consequences. While we are sitting 
around operating as we did fifty years 
ago, a communications revolution, 
population explosion, and dramatic 
world changes are swarming around 
us. The ARRL seems to doggedly 
resist change, and m addition sweeps 
the problems under the carpet when 
they should be laid out to view. We 
should ask the help of some of our 
very competent amateurs who are not 
League members in solving our prob- 
lems, Read the Who's Who of Ama- 
teur Radi<} and you will find thou- 
sands of names that would add pres- 
tige to our organization in addition to 
bringing real talent to revitalize the 
league. 

What ideas do you have? Write 
your director, demand action, and 
send a copy to 73. Let's revitalize 
amateur radio and make it the 
healthy, respected entity it used to he. 

. . .WoOl 

Mr Chapin has some interesting con- 
structive ideas regarding the League 
which need airing 73 welcomes such 
comments from any reader, pro or 
con the League and any other matter 
of vital interest to all amateurs. 




CW KEYER and 
MORSE MEMORY UNITS 

Data lingineeriug Inc. has come out 
witli a pair of keyers that may just 
revolutionize the whole keyer field. 




The Space-Matic 21 keyer is designed 
to work with any key or paddle, but 
in particular with the Data Lngineer- 
ing solid state electronic key. When 
both dot and dash paddles are 
touched the keyer alternates dots and 
dashes, The spacing between dotv 
dashes, characters and words are auto- 
matic and fixed in length, assuring the 
most beautiful CW youVe ever sent. 
The keyer has sidetone built in and 
a reed relay to key the transmitter. 




The Memory-Malic 500 has all of 
the same features of the above plus a 
500 bit memory which will handle 
about 50 characters. Imagine what a 
difference this can make in a contest! 
You can put in the signal report, 
section and date to be sent to each 
contact automatically, so all you have 
to add is the call and time by hand 
and you are on to the next contact. 

Two meter repeater owners may 
like using this for identification, as 
may remote base users on the VHF 
and UHF bands. 

When you are loading the memory 
with a CQ call or a contest exchange. 
a side tone lets you know when the 
memory is near full by rising in pitch, 
A steady tone indicates it is full, The 
message in the memory can be sent 
back at any time at any speed from 
3.5 to 85 wpm. Will we he hearing 
even sideband stations being identified 
every ten minutes with a short burst 
of weak tone from these memories? 
Will RTTY operators flip one of these 



in to give the CW identification re- 
quired? 

Prices are very reasonable for these 
two devices. The Space-Matic 21 
keyer is S89,50 and the Memory- 
Matie 500 is SI 98.50. Write to Data 
Engineering lnt\ . Box 1 245 , Spring- 
field VA 22151 for specification 
sheets. 

Automatic Wire Stripper and Cutter 




Radio Shack is offering u new 
Automatic Wire Stripper and Cutter in 
their line of Archer tools which they 
say strips #24 to #12 gauge wire 
perfectly in a second. 

To operate the wire stripper you 
simply insert the wire, squeeze the 
insulated handles and release. Insula- 
tion is removed cleanly and com- 
pletely without nicking or breaking 
wire. A strip gauge guides the wire to 
the correct portion of the blade and 
assures a uniform stripped length 
every time. 

The Archer Automatic Wire Strip- 
per and Cutter is priced at $4,95. 

Archer tools and accessories are 
available exclusively through Radio 
Shack's more than 1 100 stores in 4<> 
states and Canada, or by mail. 



PROTOTYPE BOARDS 




Experimenters, rejoice! Maratron 
(Box 777, Dallas TX 75221) has come 
up with just what you are looking for. 
Prototyping boards designed for tran- 
sistor and 1C circuits. They have pat- 
terns for 4 lead transistors, DIP ICs, 
and TO-5 IC's of 8 and 1 leads. Dot 
patterns available for using discrete 
components, too. And all boards are 
reusable. Write and say 73 sent you. 

Security Catalog 

Amateurs interested in working up 
a nice little second income could do a 
lot worse than getting into the secur- 
ity business. There are few offices or 



stores, or even homes for that matter, 
where some security system might not 
be needed. Wouldn't your wife sleep 
better if your home were protected 
against intrusion and fire? One of the 
big problems for anyone wishing to 
get into this fast-growing field has 
been one of getting information as to 
available equipment. The Mountain 
West Alarm Supply Co., 4215 North 
1 6th Street, Phoenix AZ 85016 has a 
free catalog (64 pages) of the latest 
security gadgets and, armed with this 
book, you can go into business for 
yourself. Please mention 73 when you 
send for that catalog, okay? And 
please remember where you got the 
idea to do this when you are rich. 
Don't be a fair weather friend. 



FREQUENCY MARKER DELUXE 




100 kHz markers have been around 
for a long time, but they are inade- 
quate to meet the demands for band 
edge marking and calibration with 
today's split up ham bands. How 
many operators know for sure exactly 
where the 3825 band edge really is? 
Or 14275? 

Large scale integrated circuits make 
a low cost (relatively) frequency mar- 
ker possible today which starts at 400 
kHz. splits that to 200 kHz, 100 kHz. 
50 • * • 25 - • < 10... and even 5 kHz! 
Data Engineering Inc. has announced 
just such a unit and is marketing it for 
$32.95 complete with built-in battery 
holder and a five year guarantee, The 
rnarker, less cabinet and stuff is avail- 
able wired, tested and calibrated for 
$22,95 ... or even in kit form for a 
lowly S 19.95. It runs from four pen- 
light cells. The uncabineted one 
should be fine to build into your 
receiver if you can figure where to 
borrow a few mils of 6 volts. The 
square wave output of the marker 
rings out clearly even above 1 50 MHz. 
so it can be used for zeroing in those 
FM crystals. The calibrate screw driver 
control on the front panel is for 
touching it up against WWV. 
1 Spec sheets are available from Data 
Engineering, Box 1245, Springfield 
VA 2215 L 



TELL OUR ADVERTISERS 
YOU SAW IT IN 73! 
. . .even if you didn't 



More New Products 

NEW TONE BURST ENCODERS 
ARE DIRECT POWERED 

The Ross and White Company has 
announced two new Tone Burst En- 
coders that are powered directly from 
FM, 2 meter transceiver power sources 
in transmitting repeater access signals. 

Keyed by closing the transmitter 
microphone switch from the 12 volt 
dc keyed source, the Encoder gener- 
ates a half second tone burst which 
modulates the transceiver and auto- 
matically activates the tone allowing 
activation of tone access. 

Two models are available. The two 
tone model TE-2 sells for S3 9.95 and 
the five tone model sells for S49.95 
postage paid. Both are sold on a 10 
day trial, money back guarantee basis. 

Installation of the TE-2 and TE-5 is 
relatively simple using the complete 
instructions provided for your make 
and model of transceiver. The battery 
powered models will continue to be 
available for hams preferring that 
arrangement. 

For full data including specifica- 
tions, write direct to the Ross and 
White Company, 50 West Dundee 
Road. Wheeling IL 60090. 

Motorola's HEP Introduces LEDs 

Light emitting diodes are now 
available to the hobbyist-experimenter 
through Motorola's HEP semicon- 
ductor line, with the introduction of 
four new light-emitting diodes, three 
visible red and one infrared device 
(P2000. P200K P2003 and P2002). 
These devices are ideal for digital 
clocks, frequency counters burglar 
jinn*, panel lights and on/off in- 
dicators. The devices are available now 
at authorized HEP suppliers nation- 
wide. 

NEW2M FM TRANSCEIVER 




A built-in tone burst encoder is 
featured in the new Ross and White 2 
meter FM transceiver Model RW-Bnd 
now available from the Ross & White 
( o.. Electronics, 50 West Dundee Rd„ 
Wheeling IL 600^0. The built-in tone 
burst encoder provides quick und easy 
access into tone activated repeaters 
now becoming common across the 
country. Three tone selections are 



provided. All tones are factory preset 
to commonly used frequencies but 
can be easily reset. 

A front panel power selector switch 
lets you choose power output for 0.1 , 
1.0, and 1 0W. Another switch allows 
12 channel capability. For those who 
do not wish the tone burst function, 
the rig is available without it, and the 
encoder may be added later as an 
accessory. The RW-Bnd comes with 
mike, mounting bracket, and four 
channel combinations installed. 

MEMORY IC r S 

Repeater control and CW keyers 
with pre-recorded message circuits are 
advised to investigate Intel Corpus 
sixty-four bit memory and binary 
decoder ICs. These are random access 
or addressable memories. Series 
3101-3104 memory and 3205/3404 
decoders: info via Inteh 3065 Bowers 
Ave., Santa Clara CA 9505 L 

NEW SWL RECEIVER 




Heath of Benton Harbor has come 
up with a new SWL receiver, the 
SW-717. It covers BC through 30 
MHz, has a built-in speaker, and tun- 
able bfo to copy CW or SSB, It looks 
good for the Novice or as a second 
receiver for the occasional SWL in all 
of us. Write to Heath in Benton 
Harbor Ml 49022. 

DIGITAL MULTIMETER 




Triplett. after all these years of 
being first in the meter biz, has come 
out with a digital v-o-m! Billed as a 2 l 4 
digit meter, the last figure tells you 
whether the number is above or below 
five. The price is W/i eentibucks, 
which nukes it \\ little high for the 
average ham shack and probably of 
more interest for lab or service shop 
use where the time saved by using this 
meter could eventually pay for it. 
Triplett, Bluffton OH 45$ I 7 will be 
delighted to tell you all about it and 
ecstatic if you buy a few dozen. 



1W FM TRANSMITTER 

Avcom has come out with just the 
thing for those who want to go FM 
but cannot afford to. The FM-201 is a 
miniature 1 W transmitter that can be 
mounted inside any of the high-band 
monitor receivers to make an instant 
transceiver for under $200, Or if 
walkie-talkie is your bag, any of the 
portable high-band receivers and this 
rig will make a hand-held unit for 
under $100. Multi-channel operation 
is possible; and with the 10W power 
amplifier, a handy walkie and mobile 
combination is easily within the reach 
of most hams 1 finances. Contact 
Avcom at P.O. Box 29153, Columbus 
OH 43229. 

RECTIFIER INFORMATION 

Hams working in RTTY. FM, and 
those experimenting with logic may 
find a new Motorola silicon controlled 
rectifier useful in low power switch- 
ing, detection and sensing, and control 
functions. These units draw very little 
current from the circuit and are less 
than one tenth inch in diameter. Write 
to the Technical Information Center, 
Moton/la, lnc ry Semiconductor Pro- 
ducts Div., Box 20924, Phoenix AZ 
85036 and ask for info on their 
Micro-T MCR051 through 054 series. 

3 kW Generator 




A new air-eooied, 3 kW gasoline- 
driven electric generating set was an- 
nounced by the Onan Corporation. 

Available in both manual start and 
remote start models, the new model 
3.0NB provides 3 kW of 120/240V, 
60 Hz, single-phase, 4-wire electric 
power at 1800 rpm. All models are 
reeonneetible to deliver rated output 
at three different voltages 120V, 
2-wire: 240V. 2-wire, or I20/24QV, 
3- wire - permitting the user to em- 
ploy equipment of different voltage 
requirements through a simple wiring 
change. 

Aji important feature of Onan's 
new Model 3.0NB is the single- 
manufacturer construction through- 
out. The air-cooled engine, revolving 
armature generator and (when used as 
a standby unit) the matching auto- 
matic load transfer control are all 
designed, built and tested by Onan to 
operate together as a single-integruted 
system. Onan Division of Onan Cor- 
poration, 1400 73rd Avenue, N.E., 
Minneapolis MN 554 32 ; 




What with the emphasis on upgrad- 
ing one's license due to incentive 
licensing structure, it behooves the 
amateur to learn, not memorize, his 
electrical theory. When test time 
comes and the Man is staring at you 
and the temperature in the room 
creeps to 120°, your memory can 
faihbut not if you really know what 
you are talking about. You can read 
books or attend classes, but there is a 
lot to be said for practical experience, 
too. 

One way to get this experience is to 
operate your station, but twisting 
knobs and watching meters bob a- 
round only goes so far. If you want to 
know how to operate your rig, read 
the instruction manual which should 
have come with it. If you want to 
know how your rig operates, read the 
instruction manual section entitled 
"Theory of Operation." It's easy to 
quickly read a few paragraphs, but try 
this way instead. It will take longer, 
but it is better for anyone who wants 
to learn. 

Disconnect the rig and open it up, 
but leave the ground wire connected, 
Use all safety precautions. Now with 
the manual in front of you, read the 
section slowly and where it says plate 
tank coil, find it in the rig and touch 
it. Examine how it is placed. Is it 
parallel to any other coils, or perpen- 
dicular? Is it shielded or in The open'? 
Notice parts placement in the rig and 
also how they are placed on the 
schematic. To become familiar with 
these pictures will make the FCC tests 
easier and also you will be able to 
read any of the amateur magazines 
with greater enjoyment. Also look for 
the different components mentioned 
in the theory section of the manual If 
C6 is a bypass capacitor, what is it 
bypassing? What is bypassing? Why 
bypass at all? Any terms that are 
unfamiliar or vague should be looked 
up in a handbook or other references. 
Even after looking at your own rig a 
few times and perhaps a few others, 
and then reading the pages of this or 
other magazines, you might recognize 
a section of the schematic. It may be 
an oscillator stage, or an i-f. In time, 
the different sections become connec- 
ted in your mind and you will know 
what the author has in mind. Of 
course, you should read his comments 
about the theory of operation of his 
unit, also. 

For many - Novices and Generals 
alike this can open a whole new 
dimension in our hobby. An aware- 
ness of what takes place behind the 







rint ev 



I have finally given in to my carnal 
desires and am begging for a chance to 
read 30 untouched issues of 73. I had 
to decide whether 1 wanted the Gun- 
smoke or the Extra Class Study 
Guide. I guess I like fun more than 
work. Seriously, I used the Advanced 
Class Study Guide and passed with 
only a week of study, This fact did 
not change my views on the horrible 
nightmare of incentive licensing, how- 
ever. 

As I now have a new call, W71NH, 1 
feci like an old timer and can now give 
out my opinions with the rest of 
them. WB £ >FIN in the Oct, issue men- 
tioned only a few of the rotten acts 
which take place on 20 meters. I used 
to think 40 AM in the early sixties 
was mayhem. I cannot even speculate 



brushed aluminum panel is valuable 
not only for assistance in passing the 
next higher ticket, but it adds enjoy- 
ment and comprehension of the Jour- 
nals, Never overlook construction ar- 
ticles or articles of electrical theory. 
These are what the hobby is made of. 
As you become more familiar with the 
theory, you might want to try a small 
construction project. Nothing fancy, 
perhaps a field strength meter (meter, 
diode, and a choke). When it turns out 
right, the next project might be a little 
more complicated, like a one transis- 
tor code practice oscillator. Maybe 
you can even design one yourself, 
Then maybe a small QRP transmitter. 
Speaking for myself. I was a ham for 
over ten years and never built more 
than two kits. Then, about a year ago, 
I built an antenna. Then a CPO and 
monitor, Then a field strength meter. 
Then a QRP transmitter. There really 
is nothing that can compare with the 
feeling of satisfaction that comes from 
communicating with someone on a rig 
that you built yourself. It Is a warm 
glow that spreads up from the gut to a 
dizzy sensation in the head. It hap- 
pened to me on my first QSO with a 
100 mW transmitter. I'm getting the 
bug to build and i know what I'm 
building, and why it works. 

When you face the examiner the 
next time, you'll walk in with confi- 
dence, knowing you have the know- 
ledge at your fingertips. After all, 
you've been working with this materi- 
al for some time and you have made 
electronics a part of your life, not just 
another pastime. 

...KINUN 



why hams' manners have deteriorated 
so much lately. I could not afford SSB 
equipment and was inactive until re- 
cently and the change in operating 
habits is startling, to say the least. 

Everyone seems to promote their 
own interests these days, so I have a 
few proposals': 

1 « 1 cannot afford a tower or a beam 
as I am now paying back all my law 
school debts so all beams and quads 
should be outlawed. 

2. My transceiver only runs 200 watts 
PEP so that should be the power limit. 

3. I did not notice the code 4£ hump" 
of ten words per minute but I am 
rusty now so the 20 wpm requirement 
for the Extra must go. 

4, I am too dumb and too busy to 
homebrew my equipment so all ques- 
tions on the exams concerning theory 
except those on antennas and feed 
lines should be removed. (For some 
reason I understand SWR.) 

5, As I just finished three years of law 
school, most questions on the exam 
should be from pertinent FCC and 
international regulations. I think I 
could pass the Extra exam and be on 
someone's honor roll if this were 
done, 

Steve Guelde W7INH ex K8RSX 

Cheyenne WY 

As a professional language educa- 
tor, I want to congratulate Gilbert 
Ford on his excellent article, "Say 
Coo, Say Coo, Day Eekees," (Septem- 
ber, Page 107). It is well written, good 
content-wise, and - hopefully — use- 
ful- May K too, encourage amateurs to 
try even a few words of another 
language. It pays handsomely in 
friendship if you'll just try. 

Philip D. Smith W3DZR 
West Chester State College PA 

This is a comment and suggestion 
about your proposed ^handbook" for- 
mat. It is basically an exellent idea. It 
seems to me that many advertisements 
are almost useless. They say someone 
is selling such and such, give a price 
and address and perhaps a sales pitch. 
On the other hand I suspect most 
hams and experimenters have some 
difficulty obtaining technical data on 
components. Do you suppose that the 
component manufacturers or suppliers 
could be persuaded to devote some of 
their advertising space to data sheet 
type stuff, For example, the ad in the 
October issue listing a bunch of semi- 
conductors is useful to someone shop- 
ping around for the cheapest price on, 

Continued on page 10 



LETTERS 



CONT, 



say, a FET for a VIIF front end, but I 
would rather see, and might sooner be 
tempted to buy, an ad with data on a 
single device or family, with prices 
and an address at the end. 

Hill Rutiser 
Brandy wine MD 
Good idea! 

i 

DEPARTMENT OF 
AMPLIFICATION 

1 want to thank you for the nice 
write-up you did on our alarm. One 
thing you didn't mention in the article 
which is important, is that our system 
(when used with your ear's horn) 
causes the horn to pulsate in a "beep- 
beep-bee p v " fashion so that it cannot 
be mistaken for a stuck horn. It may 
seem like a small detail, but we feel 
it's a very important one, 

Walter Scudder Jr. 



Technical Product Development, Co. 

Mev NJ- 



pm 
Nu 



I just finished reading Gilbert 
Ford's article in the November issue, 
* L Let's Revise the Morse Code/' He 
makes a very good ease, but we all 
know it will never happen. However, 
some rather interesting conclusions 
can be drawn from Figures 2 and 3 
(bit length of letters and frequency of 
occurrence). Just nine letters (E-T-l- 
A-N-S-R-D-H) constitute 659? of ah 
letters used according to the 'frequen- 
cy of occurrence" (Fig.3). These same 
letters have a bit length of 10 or less. 
Mr. Ford makes the valid point that 
the "momentary speed burst effect' Is 
the ultimate limiting factor in any- 
one's ability to copy code. Any ham 
who can copy 1 3 wpm already has the 
ability to copy these nine letters at 
better than 20 wpm. It seems reason- 
able that every ham could copy over 
20 wpm by concentrating practice on 
these nine letters until he could copy 
these at an average speed of 35 to 40 
wpm. 

Now, if we could get our friends at 
Newington to include 15 minutes of 
ETI A N-S R D H at 40 wpm as U 
standard part of daily code practice 
we would soon all have "Extra" class 
licenses and the need for confusing 
"sub bands" would vanish! 

Robert B. Bakei WA7NCT 

Billings MT 

That Heath kit 15 MHz counter 
took me 5 hours at the most, and 
worked first time. Now my pupils 
won't believe any other kind of fre- 
quency meter. Fni not an experienced 
assembler I'm a Physics teacher; I 
pick up the iron when I feel in need of 
therapy. 

Bill Jams GM8APX, GM6AGF/T 

Dall Suhool 
Perthshire, Scotland 

Re the Washington tower case, page 
5 October issue, I have sent along a 
modest amount to help in the case. It 



is important to all of us to cooperate 
in these lower eases as they arise, in 
order to establish as many favorable 
legal precedents as possible. They will 
be needed in the future, as public 
opinion against towers and poles in- 
creases. The power and telephone 
companies are already under increas- 
ing pressure to put their distribution 
lines underground. It is anticipated 
that cable TV will, in the near future, 
expand very rapidly, mostly because 
of the extended service it offers - 20 
channels are quite likely. In time, as 
sets and antennas wear out, people 
will switch to cable TV. Eventually, 
the forests of TV antennas will disap- 
pear, and the pressure against the ham 
antenna will mount even more. (On 
the plus side, hopefully, the TVI 
problem will be eased.) Looking into 
lite distant future, and barring catas- 
trophe such as nuclear war, the TV 
frequencies will be commandeered for 
mobile use. Probably all non-mobile 
radio uses will be banned. But by that 
time, the hams' spectrum space will 
long since have been eroded. 

John P. Kiir/or KV4FY 
Christiansted, St. Croix, USVF 00820 



Thought you might be interested to 
know that my article, "Amateur 
Radio and the Handicapped," in the 
November issue was very well re- 
ceived. 

1 received personal letters' from 
other disabled and non-disabled hams 
in California, Minnesota, and Arkansas 
and many comments from local ama- 
teurs. 

It is not too often that articles like 
this or information for disabled opera- 
tors appears in magazines like 73. I 
wonder how many amateurs know of 
the Handi-Ham System in Minnesota 
where amateur equipment is loaned 
free .to those who need it, or the 
Handicap Net? How much of the 
transistorized and IC logic can be used 
for the biind, deaf, and physically 
disabled? There could be many inter- 
esting and quite worthwhile articles 
written in this area, 

Ron Perry WA2CCA 
Trustee W3CVT 



Having just read the plight of 
WN30S1 in November Letters section, 
1 decided Ed better not take any 
chances. Renew my subscription, take 
my money, and leave me in peace. 
(Could you get word to the Subscrip- 
tion Department about returning the 
rest of my family and my receiver, 
please?) 

All kidding aside, I really enjoy 73. 
I just hate to see you dump it on some 
unsuspecting person. From where I 
sit, the reason 73 is successful (and it 
is) is that none of the people connec- 
ted with 73 have lost the "common 
touch." Congratulations on that and 
the best of luck in your new endea- 
vors. 

James Morrison WN9FRP 

Geneva IL. 



Rather than to fight non-business 
CB over 220 MHz. a much more 
practical solution is to establish a 
"Communicator" class ham - no test, 
or modest test, crystal control on 
assigned frequency, modest power, 
transmitter adjustment by other class 
ham or 2nd Phone. Rather than to 
open a Pandora's Box - to my mind it 
will stimulate other class ham growth, 
provide commercial incentives now 
lacking on 220, stimulate observance 
of radio regulation rather r than to 
make the citizen a criminal as is now 
the case by multitudinous regulations, 
low power, and skip band tempta- 
tion - certainly a hot potato for the 
FCC — with neither enough man- 
power or money to enforce the regula- 
tions. 

We as hams need more of us when 
it comes to international frequency 
conventions, e,g, 1 or 2 million rather 
than Vi million to provide public 
service iri time of trouble or disaster, 

John K. Laasig W5IOV 
Houston TX» 

1 just received my long awaited 
November issue of 73, but. alas!! 
What happened to the mobile theft 
alarm mentioned under "FM" on the 
cover? Did I not read the fine print? 

JohnH. Bauer W4AWM 
Arlington VA. 

Someone stole it 

Sorry to have neglected to renew 
my subscription. Certainly would not 
want to be without 73. it's tops. At 
my age (75) discretion may be the 
better part of valor, so a 1 year 
renewal will suffice. Have been ham- 
ming since 191 1 and still enjoying it 
immensely with the help of 73. Long 
may it wave. 

Edward J. Gallagher WLDD 

Qiuncy MA, 



FM PRO AND CON 

I have received your information 
that my 73 magazine subscription ran 
out. Thanks. I received all issues and 
thanks on that. You run too much on 
your pet FM, FM Repeaters, and that 
cuss hog talk junk. You call it side- 
band. I would not have any of such 
junk in my shack. Only two issues of 
73 had any ham dope on AM. 

When you publish a lot of AM 
Trans, construction then I will sure 
subscribe, 

Geo. Bali 9BFU 
Omaha NB 

1 know you want to retire, but 1 
must say it is a great relief to have you 
back at the helm of 73 once again. 
Now perhaps we can get out of the 
FM rut. Not that Em not interested in 
FM, but too much of one thing bores 
me to death. I'm confident that 73 
will continue to receive periodic re- 
newal checks from this QTH. Al- 
though one of your subscribers from 
issue #1,1 must say i nearly jumped 
ship this year. 



Hopefully your annual surplus issue 
will once again have articles about 
surplus in it! Hopefulh they will be 
written by those superstars of 73 such 
as Roy Pafenberg and LeRoy May. 
Ah. those were the good old days. . 
articles about RTTY. SSB. CW. an- 
tennas, new fangled domaflotchies 
and old circuits . . . and an occasional 
article about FM. Bring 'em back, 
Wayne, 

Kenneth D. Grimm K5KBH/4 

Sweet Briar VA 

FM? What is that! 

In regard to W A i LOT letter in Nov. 
1971 issue let me say I agree with him 
fully. I would like to see a little less 
FM - more Bob Manning and more 
YL candid shots. 

Greg Bodker WN8IZM 

While we have had hundreds upon 
hundreds of letters from readers who 
are having the time of their life as a 
result of reading about it in 73, we 
have yet to get a letter from anyone 
who has said we mislead them about 
the fun to be had on FM. Were with 
you on more Manning and more 
girls . , ; heh. heh. 

I wrote the article appearing on 

page 63 of the November issue of 73. 
Several persons have asked me, on the 
air, about a deletion on page 65 of 
the article. You might want to add an 
addenda in a future issue to the effect 
that on page 65 of Nov. issue, on the 
7th line down from the top of the 
right coin m, the addition of; 5 per* 
cent to the right of the plus/minus 
sign. 

The line should read. "May IV 6 8 
QST hut /found that a ±5'"' 

Jim Talons K3MNJ 
Philadelphia PA 

Some time ago I promised a group 
of people that I would put toge titer 
some information on a series of very 
economical decade counting/display 
modules. I didn't get the job done 
until quite recently, and by now the 
IC price war has made most of the 
information obsolete. I went ahead 
and printed the stuff anyway, partly' 
just to make good on an old promise 
and partly because there nm he some 
residual value for general education 
even tf the circuits are now uneco- 
nomical to build. 

As you are in that business, you 
will know it was no more expensive, 
once the printer was tooled up, to 
produce 1000 copies rattier than the 
few I needed, and the net result is that 
I am swamped with excess eopies of 
this publication, grandiosely entitled 
Application Sfote "/ 

If any of your readers would like a 
copy for whatever use thev can 
make of it I'm ready to send out 
copies upon receipt of a i preferably 
large) SASE. It seems necessary to ask 
that any respondents refer to this 
letter so I'll be sure to know what 
they want . . . every now and then I 
get a SASE with no indication of just 



what it is that the sender would like 
stuffed in. 

T. R.Jackson W I DM U 
Box 1, Corinth VT 05039 

Looks good, TR. better print 
another thousand. 



It is amazing to see that a manufac- 
turer has come out with a rig for 220 
to 225 MHz. Some 15 years ago I 
wrote to various companies who made 
VHF gear if they might build a rig for 
this band. They all said there was no 
demand for them, I say there's no 
more demand now either. Who the 
hell do they think they're kidding. 

This only to make it easy for 
citizen banders if and when FCC 
approves or disapproves. 

I know that you along with your 
enemy CQ are strictly for CB and a 
traitor to amateur radio. The subscrip- 
tion I get of 73 magazine, I received as 
a gift. I damned sure would not pay 
for it, or CQ magazine- QST is for 
amateurs and ARRL represents us. We 
would never have lost 1 1 meters ex- 
cept for you traitors. 

M. Srhreek Jr, 
Kearny NJ 

The unparalleled success of 2m FM 
has increased amqteur interest in 220 
tremendously and the use of that 
band is being held hack only by the 
scarcity of equipment available. The 
recently announced C.T Power trans- 
ceiver for 220 at only $IH0 has 
started thousands of amateurs to 
thinking seriously about this band. 
Their upcoming repeater for that band 
could well be installed bv munv or 
even most of the 2m repeater groups, 
th ere by ■ pro riding to un try wide 22 
communication. 

Your faith in ARRL is touching. 
But who, exactly, did pur up a bat th- 
ro save I Im? Was it ARRL? Or was It 
Wayne Green, then editor of CQ? 
Please do go to the trouble to ask any 
old timer who was there . . , anyone 
Now, about CB. I can understand whv 
CQ might be pushing for CB since 
their S-9 CB magazine is the keystone 
of their publishing empire* but what 
explains any interest in CB on my 
part' 

The EI A 220 proposal (see Man h 
73 for complete details) is extremely 
well financed and could easily go 
through, thus permanently taking 
away a good part of our hand. M\ 
proposal seems like a good compro- 
mise and gives us an alternative. R 
member that E1A has a strong Wash- 
ington LOBBY and amateur radio has 
\0 Washington lobby at all 

I note in your last issue that you 
have been getting a bit of backlash on 
the amount of FM info >ou have been 
running. I am not particularly inter- 
ested in FM as yet but 1 rather enjoy 
reading up on what the gang is doing 
on a new facet of ham radio, At least 
it makes more interesting reading than 
"Station Activities" in QST! 



Speaking of new facets of ham 
radio, I saw some color pictures that 
Bill DeWitt W2DD had sent and re- 
ceived by slow scan TV on 14mc. He 
used a field sequential system much 
like the old CBS system with six 
frames of each color. A story 7 like that 
ought to jar some of the boys who 
figure that the state of the art has 
gotten awav past the average ham. 

frfeon B. Snow W2UN 
Rochester N V 



Thank you. thank you for returning 
the 73 newspages to the horizontal 
where they can be read without tear- 
ing the magazine apart and incurring 
serious migraine. Usually interesting 
material was becoming quite a chore 
to read. As .in inveterate article tiler I 
also appreciate your new system of 
beginning articles on a right-hand 
page - please continue. 

Louise Frankenberg WA3LEQ 

Pasadena MLL 

I will probably be going to the 
University of North Carolina at 
Chapel Hill. Please print a request for 
me in the letters column for a ham to 
room with on campus. Thanks very 
much and keep up the good work. 

Donald Lee Curtis \W UMI 

22 Craven St 
Ashevillc NC 2800ft 

Thanks for the reader service and 
the large, easy -to-read print. Inciden- 
tally you discontinued the ''sideways'" 
printing just in time to restore my 
sanity and lower my blood pressure. I 
don't like CQ< and QST print is too 
small so I'm depending on 73, 

Arthur idekerW5CAM 

Pine Bluff A R. 



How about a complete Novice sta- 
tion - niuybe in several 73 articles or 
perhaps a small booklet to follow the 
Study Guide? Have been building 
0ST : s QRP Rig myself, but wouldn'1 
it be fun to build something in a 
complete package aimed directly at 
the young Novice? Maybe something 
that could be used as a club project. 
Pd be the first. 

D. K. Howard 

155 Credent St. 

Kast Bridgewater MA 02333 

Let's hear from some builders 
about this. A club project is a great 
wax to involve Vovices. 



How come you had nothing on the 
story behind the cover of Nov. '71 
issue.* Most hams Jail single like me 
and most married) appreciate the finer 
things in life and wish to enjoy these 
pleasures to the fullest! FB on the 
mug. too. 

Rliss k inner ft \8ZI0 
Toledo OH 



Many thanks for a good year's 
reading, Best regards to all at 73 and 
keep up the mod work. 

DougZL2AWF 

Vetorte NZ 



™ 



» 



Emptor? 



p>? Ql***J2 *>< 






CM*#j 



Price — $2 per 25 wt>tds for non- 
commercial ads; $10 per 2 5 words for 
business ventures. No display ads or 
agency discount. Include your check 
with order. 

Deadline for ads is the 1st of the 
month two months prior to publica- 
tion. For example: January F lst is the 
deadline for the March issue which will 
be mailed on the 10th of February. 

Type copy. Phrase and punctuate 
exactly as you wish it to appear. No 
all-capital ads. 

We will be the judge of suitability of 
ads. Our responsibility for errors ex- 
tends only to printing a correct ad in a 
later issue. 

For $1 extra we can maintain a reply 
box for you. 

We cannot check into each advertiser, 
so Caveat Emptor, . , 



SB 200 HEATHKIT kilowatt linear 
amplifier S 1 50. 41 5-593-7369. 
W6KJG, M. Harp, 1120 Furlong St, 
Belmont CA 94002. 

SELL: Heath Transmitter HX-10, 
Heath Linear Amplifer HA-10, manu- 
als, extra crystals, Dow key relay, 
package $300.00, firm. Mint condi- 
tion, p re-wired, no mods. Bill 
Robinson. 1640 Wandering Drive, 
Monterey Park CA 91754. 

V H F -FM FREQUENCY DEC A LS 

most used frequencies. Peel off & 
stick on, S1.00 postpaid. Check or 
money order. Electronic Systems, 
Inc.. P.O. Box 11208, 1518 Gregg St, 
Columbia SC 29211. 

RADIO-TV SHOP SELL, Retirement. 

All instruments, parts, hand tools, 
Sams Fo to facts, books, Caddy I-Com 
& 2 -way. Have names - Simpson, Pre- 
cision, Sprague, Seco, Sencore, Jack- 
son, Paco. Check VA for funding. 
BARGAIN. Must sell before MAY 72. 
FONE: 814-652-5126 day only. Dick 
Myers, 122 W, Main St., Everett PA 
15537. 

CHANGE THE CODE? Sell your old 
(very old) wireless code gear to David 
Serette, 226 Walton St, Portland ME 
04103. 

SACRIFICE SALE - Simpson FM 
xceiver, like new, $210 includes ship- 
ping. College expenses force sale. T. 
McLaughlin WB4NEX, College Box 
622, North Manchester IN 46962. 

WANTED - Collins 30S1 Amplifier. 
State condition. Sell or trade BC-348, 
RAL-7 complete. Call or write 
WB5EVN, Herschel P. McCuUough, 
4300 Bryn Mawr, Dallas TX 75225, 
214-691-3338. 

COLOR ORGAN KITS $7.50. IC 
Power Supply Kit $2. ICs $.25. Com- 
puter Grade Electrolytic Capacitors 
135. XMTR Transistor TRW PF3690 
SI. Used Variacs, Nuvistors, Catalog, 
Murphy, 204 Roslyn Ave., Carle Place 
NY 11514. 



SELL: HX-10, $180,00; HQ-170C, 
$150.00: Speaker, S20.00; Package 
$330.00. Kilowatt linear, $100.00; 
Supply, $85.00; Package $145,00. M. 
C, Mayerl, 312 S. LaFayette, Shawano 
WI 54166. 

FOR SALE - Back issues of 73, QST, 
and CW. Limited Supply. Jan. 61, 
Dec. 63, June 66, July 66 issues of 73, 
50 dollars each or all 4 for $ 175, Only 
4 left. For others send SASE for 
details. WB9HUC Gary Sima, Rt. 3, 
Box 85, Lake Geneva WI 53147. 

URGENTLY NEEDED: Equipment 
for independent missionary support 
net to handle messages for 30 Bible 
Translators in Liberia, West Africa. 
Need: Tower, 70 ft, or more, linear- 
SSB-220 or similar, 15/20 meter quad 
or beam. Donated equipment most 
welcome or send absolute lowest 
price. Also need Novice and other 
used equipment to prepare translators 
before they go to the tribes. We are 
interested in any extra equipment you 
have - even on loan basis — will pay 
shipping. Please help. Ambassadors 
For Christ Net, Box 366, Concordia 
Seminary, Springfield IL 62702. 

ELIGIBLE VETERANS build and 
keep a 25-inch Heath solid state color 
TV as part of a Bell & Howell (De- 
VRY) home study course. Gl-bill pays 
100% of the course and kits costs. 
Contact Bill Welsh (W6DDB), 234 S. 
Orchard, Burbank CA 91506. 

ALMOST FREE. Taped code lessons. 
Beginners to 5 wpm. Refundable de- 
posit on tapes, $1,00 for postage. 
Tomlinson College Radio Club, 3637 
West Grandview, Tacoma WA 98466. 

2-METER FM IC 20. Brand new, solid 
state, 12 channel, Xtaled for four, 1 & 
10 watts, module construction. With 
mike, m-mount, & cables. $225; 
K7NHE, 15112 SE 44th BellevueWA 
98006. 

ROCHESTER, N.Y, is again Hamfest, 
VHF meet and flea market headquar- 
ters for the largest event in the north- 
east May 13th. Write WNY Hamfest, 
Box 1388, Rochester, NY. 14603. 



FCC "TESTS-ANSWERS" . . . Origi- 
nal exam manual for First and Second 
Class License - plus - "Self-Study 
Ability Test" Proven! Satisfaction 
Guaranteed. Command, Box 26348-S, 
San Francisco CA 94 1 26. 

21ST ANNUAL DAYTON HAMVEN 

TION will be held on April 22 T 1972 
at Wampler's Dayton Hara Arena. 
Technical sessions. Exhibits, Hidden 
transmitter hunt, Flea market and 
special program for the XYL. For 
information write Dayton Hamven- 
tion, Dept 7, Box 44, Dayton OH 
45401. 

TR-108, immaculate with ac dc power 
cords; also 2 crystals included. Offer. 
WA9BYR, 627 Dundee Ave., Barring- 
ton IL 60010. 




AWARDS 

The Rhein Ruhr DX Association 
(RRDXA) will issue an award to all 
hams and swPs who can confirm 
contact with one of their 100-plus 
members after Jan. 1 , 1967 according 
to the following rules; First QSO with 
a member counts one point, another 
point for working him in a different 
mode (CW or SSB). A member can be 
worked as often as possible during a 
contest, and contest QSO's count two 
points. Three classes of awards are 
provided: Class t 100 points, SSB and 
CW mixed; Class II, 75 points, CW; 
Class III, 50 points, SSB, Send your 
application (no QSL's) with 10 IRCs 
or equivalent of DM5,™ to RRDXA- 
A ward-Manager, DJ9NW, Bernd 
Jurgens, D-5604Neviges, Schutzenstr. 
1 1 , West Germany. 

The city of St. Louis, MO claims 
the distinction of being number one 
for hams on DXCC Honor Roll. They 
are: W0DU-34O, W0SYK-341, 
W0CJZ-338, W0PG1-338, W0KF-332, 
WpLWG-332, WfDBMQ-332, 
W0BN-325, W0NVZ-331 > 
W0AUB-324, and W0BK-325, This is a 
total of 3,652 countries. Any chal- 
lengers? 

QSL^s for F0UG, HB9XID, HB0XID, 
3A0FN, WA4WME/LX, DL4VA: all 
handled by DI4VA, Vandergrift, 
MATCOM-DSO, APO NY 09052. 



ELEPHANT hide Leather. Key case 
$2; Billfold $7; Pocket Notecase S10. 
AH three - only $15. Beautiful gifts. 
Money back if not satisfied. Write 
ZE7JV, P.O. Box 23, Cran borne, 
Rhodesia. 



CANADIANS, Japanese gear. LOW, 
LOW prices. Free catalogue and infor- 
mation. Glenwood Trading Co,, Dept. 
A, 4819 Skyline Dr., North 
Vancouver, B.C. 

2 CRYSTAL FILTERS - F.M. Filter, 
10.7 MHz, 6 dB BW = 13 kHz, SSB 
Filter 1650 kHz LSB 6 dB BW = 2.6 
kHz. $25.00 ea. Paul Ramsden 
W1MUL, 3 Daniel Webster Dr., 
Hudson NH 03060. 

CASH FOR PC BOARD, All types of 
copper laminate wanted, 20 pounds or 
more. Bob Miller, WA8KGE, 2264 
Welch Drive, Stevensonville MI 491 27. 



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* 'Peace Through Victory, " origi- 
nated for RTTY by Don 
WA6PIR, art by XYL Maxine. 



Don Royer WA6P1R 
16387 Mandalay Drive 
Encino CA 91316 



RTTY ART 

MADE EASY 



ave you ever wished that you could 

make some of that RTTY art that you 

may have printed? Well, so did I at one time. 

It is a great deal easier than you might think. 

We (the XYL Maxine and I) have found 
that there is much basic art work available 
from which RTTY pictures may be made. 
Cartoons, the comic strips, post cards, maga- 
zines, newspapers, centerfolds and photo- 
graphs may all serve as bases for pictures. 
While these may not be the right size, an 
inexpensive child's pantagraph may be used 
to enlarge or reduce them. A portrait of 
Washington was made from the etching on 
the dollar bill. While it is not that important, 
if you have a little sketching talent, that will 
also help (or enlist your wife and friends as I 
did). 

Having decided on the subject and having 
the basic aft work the right size, run about 
four feet of paper out of your printer. Use 

■ 

the center portion of the paper for your 
sketch or carefully tape or glue (white glue 
works well) the drawing or photo to the 
paper. Trim the edges so that all is still the 
same width as originally. Now take out the 
paper from your printer and insert the 



four-foot sheet with the sketch on it so that 
it will be presented to you as it rolls through 
the machine. Carefully align the edges of the 
paper on the platen- Use your line feed to 
bring the top of the sketch into view. With a 
little practice, you will be able to tell just 
where any character will strike the paper. 









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Don WA6PIR, art by XYL Maxine. 



IAMI IA PV 1Q7-7 



13 



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point on, we generally take a red pen and 
indicate on the print where additions, cor- 
rections and any changes are to be made and 
rerun the tape (having folded the marked-up 
print and following it line by line, using the 
paper holder and line guide on the printer) 
to make the corrections, making a new tape 
at the same time. In most instances, we can 
now come up with a pretty good picture 
with a series of five or six corrected tapes. 

When overtyping the sketch, it helps to 
have a strong light directed on the sketch in 
your machine. This is particularly true if the 
contrast of the sketch is poor, as it may be 
in color photos. Also, as you will not be able 
to see the part of the sketch below the 
ribbon, we usually take a pencil and outline 
the areas where the shading will change from 
one density to another. This way you may 
be able to get a more complete picture the 
first time through. While we do not do this, 
some of the guys have found it helps to 
make Xerox prints of the original sketches 



"Fang, A Siamese Pussy Cat/' originated by Don 
WA6PIR, art by XYL Maxine. 



You are now ready to overtype the sketch, 
punching a tape as you go. 

We have found that a small selection of 
characters is all that is really needed to 
produce either outlined or shaded pictures. 
While you may not agree with our selection, 
study the letters and other characters to 
learn their individual densities. For example, 
the M and W are the darkest, followed by 
the H or X and then by the I. Thereafter, 
you can use the upshifted characters such as 
the : or ; followed by the " or - or . and the 
like, depending upon where you want the 
print to fall. In this way, you may add the 
shading that you desire or leave certain areas 
blank like this: 

MMHMHHIHIIrl::.:. :.::r:IHIHHMHMM 

going from dark to light and back to dark 
again. Keep up this process over the entire 
sketch. Remove the four-foot paper with the 
sketch from your printer and reinsert your 
paper stock. Now play out the tape that you 
have made and see what you have. You will 
probably be pleasantly surprised- From this 



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''Miss Santa, " believed to be by WA9CCP, obtained 
from W9PRO and relayed by WA6P1R. 



14 



7^ MA f? A 71 ME 



or photos and to use those for the over- 
typing, as they eliminate some shading and 
provide a black and white sketch from which 
to work. Keep the detail of the original art 
work as large as you can and don't be afraid 
to experiment with different letters and 
techniques. Do clean u£> the tapes - we 
generally do this during the first run-through 
after the overtyping is finished to remove 
the extra characters and corrections made 
during the typing. To give you some idea of 
the time required to complete the pictures, 
we put in about 20 hours for one of the long 
playmates that run 30 minutes or so. Most 
of this is in making the corrections while 
rerunning the tape. Even after they are 
apparently finished, we hang them across the 
room to see how they will look from a 
distance and then make the final tape with 
the finishing touches. 

Many of the machines in use today have 
non-overline features so we have quit using 
overlining. Stay within a 73 character line. 
Start and end the tape with a series of 
letters, a couple of carriage returns and 
about ten line feeds, as this will help the 
other guy if he is making a reperf tape at his 
end. Also, keep in mind those who have 
machines that downshift on space as well as 
those that do not do so. If you are upshifted 
and then space and wish another upshifted 
character, put in another figures character. 
Of course, the same applies when you want a 
letter following a space after an upshifted 
character. At the start of each line, we 
generally use two carriage returns, the line 
feed and two letters or figures depending 
upon how the line starts, to help ensure that 
the old and tired machines have time to get 
to the start of a new line. Again, make your 
tapes as short as possible by taking out any 
unneeded characters, extra letters, upshifts 
followed by downshifts and things like extra 
spaces or downshifts at the end of a line. 
Above all, be sure to put your credit line at 
the end, with the hope that others will 
follow your lead and keep it there. 

So if RTTY pictures are your bag, how 
about trying your hand and making a few? 
We will not only be pleased to receive them 
but the eyes here are about to give out?! 

. . .WA6PIR 




» LEADERS IN COMPACT ANTENNAS ■ 

MAXIMUM EFFICIENCY/ MINIMUM SIZE 

FOR APARTMENTS • SUBURBAN HOMES 

Marine and Portable Operation 

Packaged for APO and FPQ Shipping 

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B-24 + RK-3 COMBINATION 

3 ELEMENTS 
10-15-20 
METERS 

The features 
of the popular 

10-15-20 Meters B-24 plus the 

new RK-3 re- 

Power Rating 14Q0 Watts P. E. F. Hector kit 

iv make a u- 

nique 3 ele- 

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nation. Choose 
the combina- 
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RK-3 to your 
present B-24 
and enjoy the 
improvedgain 
and front to 
back. 




PATENTED 



Bands 



Total Boom Length 
Turning Radius 

Total Weight 

Single Feed Line 



23 lbs. 
52 ohm 



SWR at Resonance 1.5 to 1.0 max, 

B-24 + RK 3 Combination Net $94.95 
RK 3 Reflector Kit (only} Net $36.95 




Patented 



Bands 


6-10 15-20 Meters 


Power Rating 


1400 Watts P.E.P. 


El. Length 


IV 


Turn. Radius 


r 


Total Weight 


13 lbs. 


Single Feed Line 


52 ohm 



SWR at Resonance 1.5 to 1.0 max 



6-10-15-20 

METERS 

The time proven 
B-24 4-Band an- 
tenna combines 
maximum effi- 
ciency and com- 
pact design to 
provide an excel- 
lent antenna 
where space is a 
factor. New end 
loading for max- 
imum radiation 
efficiency. No 
center loading. 

Model B-24 
Net $62.95 



MULTIBAND COAXIAL ANTENNA 
for 6-10-15-20 METERS 

Needs no ground plane radials. Full electrical 
l /z wave on each band. Excellent quality 
construction. Mount with inexpensive 
TV hardware. Patented. 



Power Rating 


1400 Watts P.E.P. 


Total Weight 


6 lbs. 


Height 


IV 


Single Feed Line 


52 ohm 


SWR at Resonance 


1,5 to 1.0 max. 



Model C4 Net $36.95 

Send for Free Brochure 

If there is no stocking distributor near you 

order direct from factory. We pay 

shipping to your QTH if in Continental U. S, A. 




1001 W. 18th Street • Erie, Pennsylvania 16502 



JANUARY 1972 



15 



CONSIDERABLY 

SPECIAL 
CONSIDERING 

THE 
SPECS 



NEW 2 METER FM TRANSCEIVER 



Mode! SRC-I46 




Frequency 143*149 MHz 

(2MHz spread) 

Number of channels.... 5 

Supplied with 146.94 simplex, 

146.34/. 94 (same plug in 

crystals as SR-C826M) 

R.F. Output 1 watt minimum 

Sensitivity better than 0,4 

uv/20 DB OS. 

Audio output. *., # ,50G mw 

Meter monitors battery voltage on 

Tx, S Meter on Rx 

Current drain .400 maTx, 

15 maRxSBY 
Size..... 8^a " high x 3" wide, x IV deep 

Weight 24 oz., less 

batteries 

Options: external mic, or mic-speaker, stubby flexible 
antenna, desk top charger, leather case. 





Suggested 
Amateur 
Net Price 




Consider the new VHF-FM hand held Transceiver by Standard Communications Corp.. with ex* 
elusive Astropoint design. For complete specifications and the name of your nearest dealer, write: 

STANDARD COMMUNICATIONS CORP. 

639 North Marine Avenue. Wilmington. California 90744, (213) 775-6284 





The TT-63A as 

Display Generator 



James J. Wenskus, Jr. K2BEH 

329 Ballad Ave. 
Rochester, NY 14626 



Teletype Repeater TT-63A/FGC is an 
inexpensive and widely available piece 
of surplus equipment. Although many ama- 
teurs have purchased this unit, problems in 
getting it into operation have resulted in 
most TT-63AS gathering dust on a shelf or 
filling up useless space in relay racks. (It 
has a neat appearance and is fine for 
impressing neighbors or non-RTTY'ersJ 

This article describes a novel use for the 
TT-63A as a Teletype character- 
synchronized sweep generator. The 
TT-63A recognizes a Teletype character as 
part of its basic function. This character- 
istic is used to generate a scope presenta- 
tion in which the Teletype character is 
always perfectly synchronized, and time 
marks provided, at either keyboard or 
machine speeds. The basic concept is appli- 
cable to any other surplus Teletype equip- 
ment having this recognition capability. 
The "Selcal" could probably be used in a 
similar manner. 



These modifications will cost less than 
$5, depending on the state of your junk- 
box, and shouldn't take more than a 
couple evenings to build. 



+ I50V 



OIOI 



j 



<moi 

>4.7M 



cior 

FROM PIN 2 i/_ 

of ve u \\ 

0.1 \if 




RI02 
470K 



6SN7 



I 



-1 



CI02 
I jjF 



+ CI03 

*s 40-100 pF 
450V 



/ 



(300V/SEO 



^R 103 OUTPUT 

f 50K T & SCOPE 

2W (DC 
SAL) 



-I05V 



Fig. I. The bootstrap sweep generator. 



JANUARY 1972 



17 






40 
I 



80 

I 



120 
I 



160 
I 



START 



STOP 



INPUT 



i 



(163) 



143 mS GATE 



(R determined by RANGE setting] 



I 
I 

*4 



GAT£ 
(SWEEP) 




DISPLAY 
(MARK IS LOW) 



Fig r 2, Y waveforms and time relationships. 

A few comments are in order. Attempt- 
ing to convert this unit to a TU by adding a 
standard limiter-discriminator front end 
will not be particularly successful. This is 
due to two design peculiarities: The 
TT-63A is extremely susceptible to errors 
resulting from pulse splitting and the 1 ms 
sampling pulses coming in this hole. It 
needs a very good low-pass filter between 
the discriminator output and the trigger 
input, By the time you have added a truly 
effective low-pass filter, you will have 
probably duplicated half a TT/L without 

■ 

its benefits. Also, the chassis is too crowd- 
ed for the required extra components. 
Another unfortunate characteristic is its 
performance at machine speeds when a 
"start" pulse is lost; the TT-63A prints 
several erroneous characters before timing 
synchronization can be regained. In adddi- 
tion, if you are not using coax to your 
receiver, you may possibly pick up hash 
from the keying relay. 

None of these problems will signifi- 
cantly affect its performance as a synchro- 
nized character display generator. Adding 
the simple circuits shown in Figs. 1 and 4 
and slightly modifying your TU as shown 
in Fig, 3 is all that is required to make the 
TT-63A a truly useful RTTY accessory. 

The Bootstrap Circuit Operation 

Normally the grid of the 6SN7 is biased 
positive so that the tube is fully conduct- 
ing. This effectively removes the charge 
across CI 02. When the negative 50V gate 



from V6 cuts this tube off, CI 02 begins 
charging through D101 and R102. The 
cathode follower portion of the 6SN7 
feeds back the output ramp to the high end 
of R102 to maintain a constant charging 
rate and provide a linear sawtooth. With 
the components shown, the output is 
approximately 45V, The value of CI 03 is 
not too critical since the charging of CI 02 
occurs mostly in its linear region even 
without bootstrapping. Removing CI 03 
affects the amplitude far more than the 
linearity. It is necessary, however, to use a 
good quality capacitor for C102- don't 
use an electrolytic! R 1 03 allows the output 
signal to be balanced around ground. Some 
slight loss of signal results from this ar- 
rangement but it is effective and allows the 
scope to be switched from a cross tuning 
pattern to this pulse analysis mode without 
making centering adjustments on the 
scope. It should be noted that the start 
pulse is drastically shortened on the actual 
display . This is due to the poor risetime of 
the leading edge of the gating pulse. 

Construction 

The bootstrap circuitry is placed where 
VI, V2 and V3 were originally located. 
These tubes were part of the original tone 
portion of the repeater and are not used. 
The original 6SN7 (VI) is used as the 
bootstrap tube. One of the 6H6s may be 
used in place of the semiconductor diode 
shown in the schematic. The remaining 



TRANSISTOR OUTPUT 



I 



+I0-24V 



INVERTER 



MJE 340 f etc 



I 



TUBE OUTP UT 
6W6 P etc. 





TO MODIFIED 
TT-63A 



2N2925 



TO 

INVERTER 



Fig, 3. Modifications of typical TU output stages 
to provide proper polarity pulses to the TT-65A 

input. 



18 



73 MAGAZINE 



sockets are handy as tie points for the 
bootstrap components. Be careful when 
trimming wires on these sockets as several 
terminals are used for tie points for other 
stages. The sweep centering pot is a screw- 
driver adjustment type and can be located 
on the left side of the chassis after re- 
moving some unused tone parts. 

The pick off for the time-marked pulse 
display ts slutted from its original point to 

the junction of resistors R55, R56 and 
R57. This change increases the amplitude 
of the time markers over the original point. 
A slight negative dc bias is introduced on 
the display by making this change but the 
resulting improvement in marker visibility 
is worth this slight inconvenience. The 
resulting display has vigorous negative pips 
where the pulse transitions should occur 
and lower amplitude positive sampling 
pulses. The range control centers the re- 
ceived pulses between these negative mark- 
ers- 
Connecting the TU 

For proper operation of the repeater, 
the input to the Sehmitt trigger must go 
negative on the stop mark. A few addition- 
al parts can take care of this requirement. 
Since most TUs can be readily modified to 
provide positive mark outputs; a simple 
inverter, shown in Fig. 3., is added to 
provide positive space pulses. The new 
repeater input circuit in Fig. 4 shifts the 
resulting QV mark output from the in- 
verter to a negative mark. My measure- 
ments show the Sehmitt trigger turns on al 
-2,75 V and off at 2V. To get the unit in 
operation, rotate R6 to the position which 
gives the best blinking of the neon. This 
setting is not critical. 



-I05V 



INPUT 

FROM 

TU 




Fig. 4. TT-63A input modification to provide 
negative mark voltage for proper operation of 
V4> R6 is the input attenuator already in the 
uniL 




TU FILTERS 




PULSE 

Fig. 5. Block diagram of typical component 
interconnections. The TT-63A subpanel can be 
rewired to do the required switching. Attenuators 
can be added to balance the voltages across the 
fiiters to that of the sweep and pulse voltages so 
that the scope gain does not need to be adjusted 
when switching displays. 

Usage 

When this system is set up, you can 
readily observe distortions on incoming 
signals, dirty contacts, the poor efficiency 
of your low-pass filters, etc. If your key- 
board is in series with your selector mag- 
nets, you can readily check your own 
contacts. When 1 first tried this on my 
transistor TU, which had only 24V avail- 
able to drive the selector magnet, the 
observed pulse distortion was appalling. 
Going to a high-voltage loop made the 
pulses look as they should. The vertical 
input to the scope can be connected to 
various areas of your TU and the pulses 
chased through always in perfect sync. This 
is a truly enlightening experience. 

1 use a 5 in. scope for my monitoring. 
Anything less will make observing the 
pulses too difficult. A dc scope must be 
used in order to pass these relatively slow 
waveforms without distortion. I find that 
the pulses are best viewed if the scope gain 
is not set too high. They are easiest to 
watch when they are almost square on the 
screen. 

A very nice feature of this system is that 
you can tell if you have a legitimate RTTY 
signal tuned in and whether it is right side 
up, the right speed, etc., without turning 
on your printer. You merely sec if a 
synchronized sweep is being generated by 
the TT-63A, This is possible only with a 
legitimate signal. This certainty saves a lot 
of useless flatter, bells ringing, waste paper* 
etc. when tuning across the bands. 

_K2BEH" 



■ A Ml I A DV 1 nil 



19 




6»»>«» 



Rigs in one 

THE CTR-144 by COM CRAFT 

FIRST AM-FM TWO METER TRANSCEIVER 



No longer is it necessary to choose between 
AM and FM on two meters. Now you can have 
both in one compact unit. Join the gang on 
the new FM repeaters yet still be able to "rag 
chew' 1 with old friends either AM or FM any- 
where in the two meter band. 

ALL SOLID STATE — NO TUBES 

MADE IN AMERICA 




$389.95 SHIPPED POSTPAID! 
INCLUDES 146.94 MHz CRYSTAL 



COMPARE THESE FEATURES 



M 



TRANSMITTER: 

■ Built-in VFO (Frequency converted for stability*) 
AM and FM both crystal and VFO 
Four transmit crystal positions (8 MHz) 
12 watt input AM and FM 
High level transmitter modulation on AM 

Bandpass coupled transmitter requiring only final tune and load 
Three internal transmit crystal sockets with trimmers for netting 
One transmitter crystal socket on the front panel 

RECEIVER: 

Double conversion 

Crystal controlled first conversion 

MOS FET receiver front-end 

Integrated circuit limlter and discriminator for FM 

Envelope detector and series gate noise clipper for AM 

Built-in squelch for both AM and FM 

GENERAL: 

Separate transmitter and receiver tuning 

Built-in 115VAC power supply 

Direct 12VDC operation for mobile or portable operation 

Optional portable rechargeable snap-on battery pack available 

"S" Meter also used for transmitter tune up 

Military style glass epoxy circuit boards 

Anodized lettering and front panel 

Baked epoxy finish on the cabinet 

DIMENSIONS: 

■ 10y 4 "Wx6y 4 ff Hx7% H D 



tU.S. ONLY 

•VFO operates from 7 to 9 
MHz and is converted to 72 to 
74 MHz using a 65 MHz crystal 
oscillator, 72 to 74 MHz is then 

doubled to 2 meters, 

THE CTR144 IS AVAILABLE 

FACTORY DIRECT 



f 





COMCRAFT COMPANY 

P. O. BOX 266 — GOLETA, CALIF 93017 



□ I enclose $389.95. Please ship a CTR-144 and Manual. 

□ I enclose $2.50. Please send CTR-144 Manual only. 
Calif, residents add 5% sales tax, 

G Please send illustrated brochure and accessory list. 

FROM: NAME 

73 STREET 

MAG CITY 



STATE 



-ZIP. 



John G. Qehlenschlager K0MOC 
394D Ricketts Road 

Monterey CA 93940 



TELEVISION MONITOR 



After building a Flying Spot TV cam- 
, era, I acquired an old TV for a 

monitor. It was a typical early 1950 vintage 
set with a 10 in. screen and a 50 in. cabinet 
which a local TV repairman was happy to 
part with for $5. (Good thing I didn't have 
to pay for it by the pound!) It took only 
half an hour to modify the set for use with 
the camera. I was lucky, as it required no 
phase inverter or extra video amplification. 
But it was by no means the perfect moni- 
tor — modification required the addition of 
a SPDT switch, coaxial connector, a 75H 
resistor, and a short section of coaxial cable. 



After using the converted monitor for 
several months, I began to modify the set 
even further. The controls were in the wrong 
spot . . . why leave the tuner connected, it 
just uses more power . . . get rid of that i-f 
strip. Finally, the only thing that remained 
was the power supply, the sync and sweep 
section and the video amplifier section. Even 
the original CRT went to the junkman. In its 
place I used an 8XP4 universal substitute 
tube. At this point no one could recognize 
the original TV configuration. I had even 
considered rack mounting the residue, but 
gave that idea up in favor of building a new 




1ST VIDEO 
AMPLIFIER 
1/2 I2AU7 



2ND VID€0 
AMPLIFIER 

5CL6 



SYNC 

CLIPPER 

I2AU7 



POWER 
SUPPLY 



330 VDC 
220 VDC 

'-25 VDC 
63 VAC 



I 



CONTRAST 



SYNC 

SEPARATOR 

I/2 6CG7 






HORIZONTAL 

AFC 
1/2 6CG7 



/77 



I 




BRIGHTNESS /AC POWER 



VERTICAL 
OSCILLATOR 
1/2 6CG7 




VERTICAL 

AMPLIFIER 

6B06 



VERT 
HOLD 




VERT 
LIN 




HEIGHT 



HORIZONTAL 
OSCILLATOR 
1/2 6C67 






HORIZONTAL 

AMPLIFIER 

6GW6 



HORLZ ySNOftlZ 

FREQ JHOLD 



/?WIDTH 



BXP4 



FLYBACK 
TRANSFORMER 



I 



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HIGH 
VOLTAGE 
RECTIFIER 
1X2 



DAMPER 
6V3A 



Fig. J. Block diagram of the TV monitor. 



JANUARY 1972 



21 



HATRY ELECTRONICS 

500 Ledyard St., Hartford, Conn. 06114 

203-527-1881 

(1 Block Eist of Wethersfiefd Ave. off 

Airport Rd. f Rte 6) 

See CORKY, W1KXM orWARD, W1WRQ 

HEADQUARTERS FOR 2MFM 
Regency HR2-A, HR-2MS, HR-2S, AR-2 - 
Galaxy FM210 - Drake ML2F and TR22 - 
Clegg 22FM series 24-25-27 - All accessories 
for all rigs including crystals, power supplies, 
amplifiers, etc, 

FM GAIN ANTENNAS 

For mobile, fixed and portable operation by 
CushCraft, Hy-Gain, Antenna Specialists, New- 
tronics, Mark Products, Mosley. 

ANTENNA STUFF 

Open wire feed line — Antenna wire 18, 14, 
12 — Bare Copperweld — 14 and 12 enamel 
copper — insulators — Baluns — Lowloss coax — 
BlitzBugs — Glassline guy — Rohn #25 towers 
and accessories — B & W — Coax switches — 
Dowkey relays — 72 ohm KW twin lead. 

ALL MAJOR LINES OF AMATEUR GEAR 
We have B&W ARRL PROJECT KITS in stock 

(Canadian Amateurs Send U.S, Funds Only) 

F.o.b. Hartford 

Please Include Postage 

CONNECTICUT'S OLDEST HAM STORE 



I 



i 



I 



I 



NOW ACCEPTED FOR 

1 DAY C.O.D. SHIPMENT 



ON ALL OUR 



PRE-AMPS 



AND SOME OF OUR 



CONVERTERS 



If you need a low noise pre- amp in a hurry for communications or 
instrumentation, we can fill your order custom tuned to any frequency 
from 5 MHz. to 475 MHl within 24 hours by air mail of special deliv- 
ery. All you pay is our regular low price plus C.O.D, shipping 
charges. This rush service is also available on some of our stock 
converters. See Oct, Nov. and Dec. 1971 issues of 73 Magazine for 
our 2 page condensed catalog. Call us between 9AM and 4PM, Monday 
thru Friday except holidays (no collect calls please). If line is busy 
keep trying. 

PHONE: 212-468-2720 



196-23 JAMAICA AVE 
H0UIS.N.Y. 11423 




0(0 



FUSE 



J ll 



110 
VAC 



POWER 
TRANSFORMER! 



IZAW') K2ALJ7J 



n V1DE0 
] INPUT 



Fig. 2. The physical layout of the monitor. 



monitor. Several points came to mind while 
designing the monitor. First of all I would 
limit construction cost to a maximum of 
$50. It must not employ any parts unavailable 
to the average ham. The operational controls 
must be located on the front panel for 
convenience. The monitor must be simple to 
adjust, using a minimum of test equipment. 
Finally, it must lend itself to modification to 
suit the individual builder. 

Using these criteria, I was able to con- 
struct a monitor for $22 (less CRT). I was 
lucky enough to have a CRT left over from a 
previous project. A new 8XP4 will cost $22 
to $28- The principal item I had to purchase 
was the cabinet. I used a Premier CC-2000 
with a 3x10x27 in. aluminum chassis. The 
majority of parts came from several salvaged 
TVs obtained for the asking from a TV shop. 
Although I would have had no difficulty 
obtaining a horizontal output (flyback) 
transformer from a junked set, I chose to 
purchase a new one for $1. If you choose to 
use a CRT such as a 5AXP4 or 5FP4 
(requires focus magnet) you may want to 
use a 70 yoke and transformer, also costing 
$L 110 deflection components are also 



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OUTPUT 



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Fig. 3. To facilitate wiring, terminal strips are 
mounted in parallel rows. 



22 



73 MAGAZINE 




Monitor exterior. * . 

available commercially, AH other parts came 
from my junkbox. 

The operation of the monitor can best be 
described by referring to the block diagram 
(Fig. 1). The input may be from Vi to IOV 
negative video from any 75H source. The 
output of the first video amplifier is fed to 
the second video amplifier and to the sync 
clipper. The output of the second video 
amplifier is applied to the control grid of the 
CRT. 

The sync clipper consists of a normal 
voltage amplifier followed by a saturated 
amplifier. The output of the saturated ampli- 
fier contains only sync information (i.e. 
pulses of 60 Hz and 15.75 kHz). From the 
saturated amplifier the sync pulses are cou- 
pled to the sync separator. The output of 
the sync separator is sent to an integrator 
(low-pass) circuit (vertical sync) and a differ- 
entiator (high-pass) circuit (horizontal sync). 

The differentiator output is coupled to 
the horizontal afc (control) tube. The hori- 
zontal afc keeps the horizontal oscillator 




. . .and interior 

(blocking oscillator) locked on frequency. 
The output of the horizontal oscillator is 
modified by the 330 pF capacitor to a 
sawtooth waveform at the grid of the hori- 
zontal amplifier tube. The output of the 
horizontal amplifier is coupled to the hori- 
zontal section of the deflection yoke by the 
horizontal output transformer. 

High voltage pulses developed by the 
flyback transformer are rectified by the HV 
rectifier to provide 12.5 kV for the CRT. 
The damper suppresses oscillations in the 
horizontal deflection coil and provides an 
increased voltage (B+ boost) for the horizon- 
tal amplifier and the vertical oscillator, 

The power supply provides 330V dc at 
100 mA, 220V dc at 100 mA 5 -25V dc for 
fixed bias and 6.3V ac for all filaments. 

The power supply was the most difficult 
part of the construction project. Three 
different circuits were tried before an 
acceptable supply was achieved. The supply 
uses silicon rectifiers throughout, Normally 



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500 K 



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330 V 




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EXTERNAL ^ iN 
HORIZONTAL f») 
SYNC ^r 



120 PF 

-9 



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AA/\ *- 



EXTERNAL 

VERTICAL 

SYNC 



Fig. 4a and b. Two methods of supplying focus 
voltage/current to the CRT. 



Fig. 5. A suggested modification for sync only 
input. 



JANUARY 1972 



23 



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Fjg, 6, Schemati& 0/ the deflection and high voltage section. 



the power transformers from TV sets have 
three filament windings, two 6V and one 
5V. They were used to obtain the negative 
bias voltage using a simple half-wave 
rectifier. If your transformer has only two 
6V or one 6V and 5V windings, a voltage 
doubler should be used to provide the 
necessary —25V bias. The electrolytic 
capacitors used in the power supply section 
may have a greater capacity than those 
shown, depending upon what you have 
available; however, do not use less. 

Mounting of the CRT may present some 
problems. I modified a mounting from a 17 
in, set for my use. To simplify mechanical 
work, I obtained a yoke which clamped to 
the neck of the CRT. It required no other 
mechanical support, and there were 
centering magnets included on the assembly. 

The layout shown in Fig. 2 was used. I 
encountered no problems with stray 
magnetic fields. The vertical output 
transformer and the vertical blocking 
oscillator transformers were located under 
! he chassis. I used two four-section 
electrolytic capacitors, along with a couple 



of lead type electrolytics. There is sufficient 
room for another multisection twistlock 
electrolytic if you desire. To simplify wiring, 
10 seven-terminal (2 ground) terminal strips 
were mounted in parallel rows as shown in 
Fig. 3. Other smaller terminal strips may be 
added as desired. 

After wiring is completed, check carefully 
for errors before operating the monitor. For 
the smoke test, I recommend removing the 
horizontal output tube (6GW6) and the 
vertical output tube (6BQ6) and temporarily 
connecting the hot end of the height control 
to the 330V buss instead of the B+ boost. In 
my original model, 1 had the height control 
going to the 330V buss, but I was unable to 
adjust the height and vertical linearity 
satisfactorily. During normal operation the 
B+ boost voltage is 700V. This gives a very 
linear vertical sweep. 

The test equipment needed for checkout 
are a VTVM with high v oil age probe, an 
oscilloscope with a low capacity probe, and 
a source of l A to 10V negative composite 
video. While a scope is not a 
necessary, it is very helpful. 



24 



73 MAGAZINE 




Vertical oscillator grid voltage waveform. 



Vertical output plate voltage waveform. 



Alignment Procedure 

1. Turn on the monitor and allow it to 
warm up for 5 minutes. Keep a sharp 
eye out for overheating of resistors or 
tubes, 

2. Set all controls at mid-rotation. 

3. Connect the source of video to the 
monitor. 

4. Check each video stage for signal. You 
should he able to trace it right up to the 
CRT control grid. 

5. Check vertical oscillator for correct 
operation, 

6. Insure that -25V is available for the 
vertical and horizontal amplifier grids 
before proceeding. Then insert the 
vertical output tube. Be sure that the 
deflection yoke is connected. If it isn't 
connected the tube and the transformer 



7, 



may be damaged* Using low capacity 
probe, check the waveform across the 
vertical deflection yoke. Rotate the 
vertical hold, vertical linearity, and 
height controls and observe their effects 
on the waveform. Using the VTVM, set 
the vertical amplifier control grid 
voltage to 15V using the vertical 
linearity control. 

(heck the horizontal oscillator using the 
low capacity probe for proper 
operation. By adjusting the horizontal 
frequency, horizontal hold and 
horizontal stability there should be a 
15,75 kHz, 60 - C ^0V peak-to-peak saw- 
tooth waveform. When you are satisfied 
that the oscillator is functioning cor- 
rectly, turn off the monitor, insert the 



1/2 iZATT 



53Pf 



6CL6 



047 







123 KV 
330V 



+ 2EOV 



BLANK 

HORIZ 
SYNC 

VERT 
SYNC 



/77 



Fig. 7, The video amplifiers and sync separator /dipper. 



JANUARY 1972 



25 






1000 Hz video test square wave at CR T grid, 



Horizontal deflection coil current waveform. 



8. 



9. 



10. 



6GW6 and reconnect the height control 
to the B+ boost. 

Re-energize the monitor, again looking 
for overheating of resistors and tubes. 
Adjust the brightness control to about 
mid-rotation. The CRT should light and 
a raster should appear. With the VTVM 
(using the HV probe) check for B+ 
boost (500 to 700V) and HV (10 to 15 
kV). Adjust the width control for 100V 
on screen of 6GW6. Adjust the height 
control for a 100V peak-to-peak 60 Hz 
sawtooth on the vertical amplifier con- 
trol grid. 

By adjusting the front panel controls, 
you should be able to obtain a picture. 
Adjustment of the yoke (mine had 
centering magnets attached) may be 
necessary. If the picture is upside down 
or mirror image, reverse the necessary 
yoke leads. 

Fine adjustment may be accomplished 
by using standard TV alignment pro- 
cedures. Notice that the horizontal hold 



750 MA/800 PIV 



ZA 



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/77_L0CM 





/77 



45Q I 4 50l 




A/W 



>-Z5VDC 



63V&C 



MONITOR POWER SUPPUf 

TRANSFORMER 
PRIMARY SECONDARY 



HSVftC 



260-0-260 250 MA 

6 V 5 A 

6V 2 A 

5V 3 A 



Fig. 8. Monitor power supply. 



and horizontal frequency controls inter- 
act, as do the width and brightness, 

I get carried away using silicon diodes, 
Originally I used a 3000 PIV 200 mA diode 
for the damper. After two frustrating fail- 
ures, I used a 6V3A. If any of you more 
persistent types desire to try a silicon diode, 
use at least a 5 kV PIV 200 mA diode. If 
you use a 6V3A remember that it has a 
cathode cap and not a plate cap. It won't 
work the other way! 

As for substitution of tubes, a 6BQ6 
could be used in place of the 6GW6. 
However, with the high B+ boost voltage 
present (700V) 1 used a 6GW6. 

I used an 8XP4 universal test tube, 
although any one of several CRTs may be 
used. An 8YP4 may be used if 1 10° deflec- 
tion components are used. An 8KP4 may be 
used if correct focus voltage is supplied to 
the focus anode. An 8DP4 may be used also; 
however; it requires — in addition to a focus 
voltage - a single field ion trap. A 5 in. tube 
such as a 5AXP4, 5AHP4 or a surplus 5FP4 
could also be used. The 5AXF4 requires no 
external focus supply. The 5AHP4 requires a 
focus supply of to 250V. The 5FP4 is an 
electromagnetic focus tube. Figures 4a and 
4b show methods of supplying focus volt- 
age/current for other CRTs. 

This monitor was designed as a basic 
building block for future projects. For those 
with a master sync generator, a syne only 
input may be desirable, A suggested modifi- 
cation is shown in Fig. 5. Other changes/ 
adaptations may be made to the basic design 
to fill the requirements of the builder. 

. . .K0MOC74 



26 



73 MAGAZINE 



73 Tests 




THE ICOM IC-21 TRANSCEIVER 



he word has leaked out around the U.S. 

about the Japanese IC-20 and IC-21 
transc elvers , fueled by a handful of units 
brought back by visitors to Japan and 
returning servicemen. Now, at last, these 
goodies are being made available through a 
U.S. importer, 

Adirondack Radio was kind enough to 
lend their first sample for a test and it 
certainly was impressive. The most spectacu- 
lar aspect of the rig is the 24-channel 
frequency switch, complete with an easy-to- 
get-at board for the 24 crystals and tweaking 
capacitors immediately at hand. 

Now, while you may live in an area which 
only has one or two repeaters, those of us in 
the northeast are living in an entirely differ- 
ent world, one jammed with repeaters on 
just about every pair of channels. Though 
the 73 HQ is in a remote corner of lower 
New Hampshire, there are now about 17 
repeaters that can be used with a simple 
antenna. Three miles away, from the top of 
Pack Monadnock mountain, where we test 
out new equipment, there are a whole bunch 
more within easy reach. A 24-channel trans- 
ceiver looks awfully good for a spot like this. 

The IC-21 has so many nice features that 
it is difficult to decide which is the most 
desirable. It has an ac supply built in and 
will operate from either 115V ac or 13.6V 
dc, making it a dandy unit for both base and 
mobile applications . . . and particularly val- 
uable to the operator who wants to be able 
to use one rig both in the car and at home. 



The transmitter puts out 10 watts on the 
high power position of the output switch 
and one watt on the low position, making it 
possible to save on battery power when 
operating through most repeaters. 

Experienced FM operators will appreciate 
the variety of meters on the IC-21. Just 
above the channel switch is a deviation 
meter which indicates how much off fre- 
quency the incoming signal is. This meter is 
calibrated plus and minus 5 kHz. There is a 
control on the front panel to compensate for 
this off-channel stuff . , /a Receiver Incre- 
mental Tuning control which swings the 
receiver back and forth about 5 kHz. Since 
not all 94 repeaters are on 94 and not all 76 
repeaters are exactly on 76, this is a handy 
control to have when you are moving from 
one area to another. 

The S-meter on the receiver comes in 
handy when you want to identify which of 
several repeaters you are hearing and there is 
no identification at the moment. At our 
mountain lab site we hear W1ALE in Con- 
cord on 94 at umpteen over 9, WA1MHN in 
Somerville, Mass., at S-9, WA1KGR in Holy- 
oke, Mass., at S-8, and W1KOO on Mt. 
Mansfield, Vt., at S-I ? so you can tell from 
the S-meter reading exactly which repeater is 
being heard at any time. On 88 the S-meter 
permits instant identification between 
W1ARI, WA1KFX, K1AOI, W1ZAW, 
WAUTB,and WA1KHK. 

The S-meter becomes a plate tuning 
meter on transmit or an SWR-meter, with a 
flick of the front panel switch. There is a 



JANUARY 1972 



27 



ADIRONDACK Proudly Presents . . . 



the 




$389.00 Net 



• 24 Channel capability, 

• A new high — very useful in these days of new 
repeaters going on the air constantly. 

• Front panel — P,A. tune control — a real advantage to 
get maximum output, 

• Separate S and discriminator meter ±5 KHz — panel, 

• RJT. — control on receive - either 1 watt or 10 watt 
output. 

• S and SWR meter combined. 

• Remote VFO plug, 

• 12 volt DC or 1 10 volt AC operation. 

• AC and DC cable supply. 

• Discriminator meter — a real addition. 

• Crystals — supplied with 4 channels. 

This is an entirely new approach in 2 meter FM gear. Just 
imagine 24 channel capability, SWR meter and S meter, 
plus netting condenser on each transmit and transceive 
crystal, plus many other features original with this unit. 

Manufactured by Inoue Communication Equipment Corp* 
of Osaka, Japan, already well known to 2 meter FM users. 

Send your order today. 

ADIRONDACK RADIO SUPPLY, INC. 

185 West Main Street, Amsterdam NY, 12010 



FM YOUR GONSET 
COMMUNICATOR 



New! Plug- in modulator puts the 
Communicator transmitter on FM. 

No modification or rewiring of your 
Communicator. Just plug mto mike 
jack and crystal socket. 

Compact self-contained modulator 
measures 4" x 3" x 1 W\ 

Works with Communicator l f II, III, and 
IV, 

FM at a tenth the cost of a new rig. 

Frequency adjust for netting built in, 

Built-in tone burst available. Keyed by 
push-to-talk switch, 

$34.50 postpaid U.S,A« Built-in tone 
burst $1 0.00. Specify Communicator 
model and tone-burst frequency. 5% 
tax in California. (HC-17/U crystal 
and 9 volt transistor battery not 
supplied.) 

Send for free descriptive brochure. 



BOX 455, ESCONDIDO, CA 92025 






plate tuning control on the panel, permitting 
the plate to be peaked on any channel, thus 
overcoming the serious drop in power you 
suffer with some rigs when you change 
frequency from one end of the band to the 
other. 

The mike gain control on the front panel 
is useful for setting your deviation to match 
the repeater you are using. Some are wide- 
band, some narrow, and some compromises. 
With a little fiddling around you can find 
out what works best with each repeater and 
use that deviation from then on- 
Some of the statistics, briefly: weight 14 
lbs; size 4Yi" high, 9" x 10", will obviously 
fit under most dashboards; draws 0.2 A on 
receive, 2.1 A on high power, and 1.2 A on 
low power; uses 18 MHz crystals for the 
transmitter and 15 MHz for the receiver; i-f 
is the usual 10,7 and 455 kHz. 

An automatic protection circuit disables 
the driver transistor if anything happens to 
the antenna, thus keeping the final transistor 
from going west when the antenna is shorted 
or opens up, 

A low-pass filter on the output is de- 
signed to keep interference down to neigh- 
boring television sets. 

The IC-21 is designed to be mounted by 
means of a bracket in the car and a built-in 
folding foot stand angles it for use on the 
operating table. 

An external vfo may be used with the 
IC-21. It plugs into one side of the cabinet. 
There is a jack in the back for an external 
speaker, which is very handy for car installa- 
tions where you would prefer to listen to the 
regular car radio speaker than the smaller 
one on the transceiver, 

Since the transmitter and receiver units 
are independent of each other, a good 
technician might be able to convert this rig 
rather easily into a repeater. It wouldn't take 
a whole lot of work, The modular construc- 
tion of this rig would make such a "conver- 
sion" much easier than with most transceiv- 
ers. The fact is that you can get at almost 
everything on the IC-2L 

The IC-21 is being imported by Adiron- 
dack Radio, Amsterdam, New York and sells 
for $389.00. 

. . .K1NUN 



28 



73 MAGAZINE 



73 Tests The REGENCY 

Transcan FM Transceiver 



A scanning transceiver was the obvious 
next step in two meter FM transceiv- 
ers. There are so many repeaters in action 
today, even in the more remote parts of the 
country s that the FMer needs some way of 
keeping track of which are being used. Back 
in the old days, a year ago, when there was 
only one repeater in most areas, a simple 
monitor receiver was all that was needed to 
keep in contact. 

As 1972 unfolds we find that most major 
urban areas have four to six repeater chan- 
nels perking and, unless the FMer has his 
hand on the channel switch a whole lot, he 
misses out on most of what is happening, It 
gets to be quite a drag to reach up and 
switch through all the channels every few 
minutes. It is a lot better to have a couple of 
ICs and some transistors doing that for you, 
automatically. 

Regency has married their scanning VHF 
receiver and their very popular HR-2 two 
meter FM transceiver and come up with a 
package which does everything for you 
except keep the log. The receiver scans eight 
crystal controlled channels and, when any 
one becomes active the light turns on, the 
scanning stops and the squelch turns off so 
you can hear the station. Each of the eight 
receive channels may be locked out of the 
scanning function by pushing a button over 
the channel lamp. This is handy when one 
channel is active and you want to scan all 
but that one ... or two, etc. 

There are six crystal transmit channels 
which are selected by the buttons under the 
receive channel lamps, which leaves two 
receive channels which can share any of the 
six transmit channels with another receive 
channel. Pushing the transmit button locks 
the receiver to that channel until you push 
the "scan" button which disconnects all 
transmit crystals and sets the receiver to 
scanning again, 

JANUARY 1972 



This setup is ideal in the areas I frequent, 
g the six repeaters we use in New 
Hampshire and southern Vermont. When I 
head down Boston way I change the crystals 
for the six active repeaters down there 
(W1QFD, WA1KGS, WA1MHN, WA1NJR, 
W1HWK, and WA1KGO). If Fm driving to 
New York, which happens often, I load up 
for WA1KGQ, WA1KGR, WA1KGD, 
WA1KGK, WA1KHK, and WA2SUR. And so 
it goes, with my being able to talk through a 
selection of repeaters no matter where I am. 

The Transcan is extremely handy at 73. 
HQ where I monitor not only the six fairly 
local repeaters, but also listen for calls on 76 
and 94 simplex from passing FMers. We have 
a pot of coffee at the ready for visiting 
amateurs and do appreciate the company. 

The Transcan has also alerted me to several 
band openings which have permitted me to 
talk down into New York and even points 
further away. 

The scanning function is accomplished by 
a couple of ICs which switch the receive 
channels by means of diodes and sample the 
channels, stopping when the squelch is oper- 
ated by a carrier. There is automatic protec- 
tion of that expensive output transistor too, 
with a little circuit that senses if the antenna 
opens or is shorted and turns off the drive to 
the final. 

All in all, Regency has come up with one 
of the best fun-makers for two meter FM 
yet. I don't have time to switch through all 
the channels while Im driving to see who 
might be coming through. The Transcan 
does it for me and even the shortest blip of a 
carrier stops everything and lights up the 
active channel. The price is $319 for the 
mobile model and $349 for the desk model 
with built-in 1 17V ac power supply. 

. , .W2NSD/1 

29 



73 Reviews 
The Allied 
AX-190 

Ham Receiver 




If all receivers performed as well as they 
looked, a ham would have no trouble in 

obtaining a good one. The trick is finding 
the good receiver that is behind the pretty 
panel. The Allied AX-190 is such a one. 
Behind the brushed aluminum front are five 
printed circuit boards that hold all compo- 
nents in very neat arrangements. On one of 
them is the four FET front end which is 
rated at 0.5 /iV sensitivity at 10 dB S/N. Our 
test unit performed very well with no more 
than a longwire, and we have no reason to 
doubt Lhe accuracy of the manufacturer's 
statement. This receiver picked up many 
weak stations that other radios could not 
hear. The preselector is very sharp and 
sensitive and really peaks up signals while 
rejecting interference from strong off-fre- 
quency stations. The receiver covers eighty 
through all of ten meters in 500 kHz bands. 
There is also provision for adding another 
segment of the 3.5 - 10 MHz range. 

For those strong signals that cause QRM, 
the Q-Multiplier does an excellent job of 
eliminating heterodynes and peaking the de- 
sired signal. This feature is certainly a 
desirable one for CW and SSB ops. Signals 
here were raised by thirty to forty decibels, 
and when the rejection mode was selected, 
annoying whistles were eliminated. 

CW and SSB are received well by means 
of a four diode balanced modulator circuit. 
The first oscillator and bfo are crystal 
controlled for sharp and accurate tuning. 
The audio is clean and pure, and almost 
hi-fi — in short, very comfortable. Dual con- 



version and ceramic filler add measurably to 
easy listening. 

For those who might want to listen to 
AM stations that are outside the ham bands, 
an AM position and AM with ANL are 
provided on the function switch. Incidental- 
ly, the diode noise limiter performs very well 
to take out ignition and electrical noises 
(i.e., the fluorescent light on my desk). 

As for minor features that add to the 
pleasure of owning the AX-190, there is a 25 
and 100 kHz calibrator for accuracy of the 
smooth tuning vfo knob which has one 
kilohertz markings on the resettable skirt. 
The rig also has provision for operation 
directly off of 12V dc, making the rig 
valuable for mobile. Field Day, emergency, 
and portable use. Antenna input is a com- 
mon SO-239 chassis connector, provision for 
muting, and vfo output round out the 
features of this receiver. One other valuable 
feature of the rig is the accompanying 
instruction manual. It is complete with an 
excellent theory of operation section that 
includes excerpts of the complete schematic 
showing the various stages in their individual 
and combined design states. 

For the ham who is looking for a good 
receiver, portable, or emergency receiver, at 
$249.95 this receiver needs careful consider- 
ation. Novices in particular should keep in 
mind that a few extra dollars on the receiver 
purchase can add proportionally greater en- 
joyment to his operating experiences. And 
when upgrading his license, this receiver will 
keep its value in the station. 



30 



73 MAGAZINE 



Martin Bradley Weinstein WB8LBV 
1260 Richmond Road 
Lyndhurst OH 44124 



PHONE PHREAKS 

Ma BELL 




64T Lttle Box Blue, get on the horn" is the 
A^i all of a new band of public nuisances, 
the self-styled "Phone Phreaks" who have 
been using a small electronic device, known 
as a "Blue Box/' to defraud the telephone 
services of an estimated half million dollars a 
year. 

73 talked with Dennis Mollura at the Bell 
headquarters in New York about these Blue 
Box activities. 

First, Mr. Mollura described Blue Box 
operation: 

"They are used to call the network 
signalling function on the telephone net- 
work. If you build a Blue Box that has 
the proper tones and you know how to 
use it you could tap out the right tones to 
give the network its command; then 
you'd be able to avoid our automatic 
billing equipment. " 

These tones are the twelve dual-tone 
combinations of six frequencies used only 
for network calling frequencies, and are not 
the same as a standard Touchtone® phone 
would produce. You may have noticed* after 
dialing a long distance calj, a rapid succes- 
sion of higher-than-Touchtone® frequency 
tone-pairs lasting about a second. These are 
the network control tones, 

A Blue Box user first seizes a long 
distance line by phoning a toll-free long 
distance number, most often a directory 
assistance or IN-WATS (area code 800) 
number, then hanging up on the callee while 
retaining the circuit by generating his own 
2600 Hertz "disconnect" tone. The 2600 
Hertz tone would normally not appear on 
line until the caller has hung up, and once 
sensed, is regarded by switching equipment 



as a signal to disconnect. The captured line is 
then used to call anywhere in the world at 
the caller's whim. Most "Phone Phreaks" 
figure they're getting away with it, but the 
feeling is usually ephemeral. 

"There are three ways which we use to 
try to detect Blue Box fraud; number one 
would be plant service center testing 
(with very common electrical testing 
equipment) . , . another way is traffic pat- 
tern analyses . . , then the third way is 
computer programming. The computers 
are watching the networks and they . , m 
can spot trouble > . . and kick out a trou- 
ble report card. " 

It would appear that most of the current 
users of Blue Boxes are now at this point in 
telephone company investigations. They 
have some unpleasant surprises in store for 
them if they should be so naive as to think 
that this is as far as the investigations go. 

"When we suspect a case we can put on 
sophisticated electronic gear . . . which 
can help us track down the people. 
"We've, . . begun a nationwide crack- 
down. In 1970 there were six people 
arrested, two convicted, four cases pend- 
ing. So far this year {September}, thirty- 
three arrests, eighteen convictions, four- 
teen pending, one dismissed. In the Mon- 
tana area, a group of ten people . . , were 
using Blue Boxes. We factually, the FBI) 
moved in on them. , . they were indict- 
ed ... and arraigned, and the evidence 
was so overwhelming that seven of the 
ten pleaded guilty right off the bat, two 
of the cases are pending, and one is 
dismissed. " 



JANUARY 1972 



31 



Naturally, the Blue Box users aren't 
hurting anybody, unless you feel that having 
to pay their way yourself is an imposition, 
"People are trespassing on the telephone 
network. Tliey 're literally stealing service, 
and actually increasing the cost of tele- 
phone service for people who do pay. I 
can describe this as like a guy getting on a 
turnpike and not stopping at a toll booth. 
He's creating a demand for service, but 
he's not contributing his share, "Our 
losses due to Blue Box fraud . . . we T re 
estimating at about five hundred thou- 
sand a year, *' 

With a half million dollars a year at stake, 
why not just clamp right down? 

"One of the reasons that we gather 
evidence for so long, like in the Montana 
case, is to establish what the person's 
calling pattern is f to try to determine 
when he got the box, how often he used 
it, and where he called. Once we establish 
a pattern and can pinpoint when he got 
the box, then we go for full restitution. 
In cases we Ve been able to get it. *' 

So far, no amateur radio operators have 
been involved, but the people who were in- 
volved might well have become hams. 

"Of the thirty -three people arrested this 
year; twenty of them were students, one 
was a private detective, one was a com- 
munications man, and most of the rest 
had electronics background interest, ** 
What is the phone company position on 
the use of these devices? 

"We consider this a very serious matter. 
People are trespassing on the telephone 
network. We do have means of detection, 
and we are confident that we are eventu- 
ally going to catch them all When we get 
them, we are going to press to the fullest 
extent of the law, and we're going after 
full restitution of the money we've lost so 
ar r 

Amateurs who have been using 2600 
Hertz notcl} filters and 3400 Hertz roll-off 
low pass filters in conjunction with phone 
patching have most of the protection neces- 
sary to prevent accidental interference with 
telephone service. 

'The Blue Box enables you to place calls 
without charge. There's another electron- 




Chester County (PA) Detective Ronald Johnson 
(right) displays an illegal "blue box" used to 
bypass toll charges and seize long distance tele- 
phone circuits, Johnson and Chief of County 
Detectives Eugene Sharpe (left) were part of a law 
enforcement team (September 21 ', 1970) which 
raided several Chester County residences of suspec- 
ted "phone phreaks." The "phreaks" use home- 
made electronic generating devices such as the 
"blue box" to place free long distance calls all over 
the world, sometimes for hours at a stretch. Four 
persons were arrested in connection with charges 
ranging from toll fraud to impersonation of tele- 
phone company employees and f in one case, 
wiretapping. Authorities said "several carloads " of 
illegal equipment were confiscated, some of which 
is shown here* 

ic device which would enable people 
calling you not to he charged. I'm sure 
you're very familiar with this, I have an 
article written by you in the September 
73. There was some concern. Someone in 
the telephone company spotted the ar- 
ticle and was somewhat concerned about 
iL I checked it through and it's a legiti- 
mate article, ft has a disclaimer at the 
end t . J here s no problem. " 

Most of the details concerning the particu- 
lars of design of the equipment used by the 
phone company in tracking down the Blue 
Box Banditos must, of course, remain confi- 
dential for the moment. 73 will continue to 
monitor developments in the case of the 

Phone Phreaks versus Ma Bell, and will release 
pertinent new developments as they become 

available . . .WB8LBV 

References: 

ENQUIRE, October, 1971, p. 116 "Secrets of the 
Little Blue Box" by Don Rosenbaum, 
73, September, 1971, p. 117, "A DC Isolator for 
Phone Lines" by Martin Weinstein, 



32 



73 MAGAZINE 







Frankly we have a point to make. 
For years businesses have been 
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in your shack. Why leave your 
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Interchangeable announcement 
tapes let you make different mes- 
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in monitor lets you screen calls. 
Simple 2 wire installation. 



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LABORATORIES 

TV And Communications Antennas Since 1921 
Asbury Park, New Jersey 07712 201-775-7252 



AFSK 

REVISITED 



Marc I. Leavey WA3AJR 
941 2 Adelphi Road, ApL 202 
Adeiphi MD 20783 



Many hams are lured into the wonder- 
ful world of Teletype by the prom- 
ise of unattended autostart, automatic mes- 
sage handling, or the ability to send fancy 
holiday greetings. They often find, how- 
ever, that such operation is practical only 
on VHF, where non-drifting, non-fading 
signals make such transmissions easy. Such 
a finding is not wholly true. Although 
sophisticated converters can work wonders 
on the lower frequencies, advanced cir- 
cuitry is hardly the answer a newcomer to 
Teletype needs* Unfortunately, that is 
about all he has gotten — until now. Unlike 
earlier circuits, the audio frequency shift 
keying (AFSK) generator described here 
uses a bare minimum of parts. It gives a 
reasonably good sine wave output and - 
using the keying technique included — a 
minimum of transits or bias. The keying 
technique referred to is the application of a 
new device, the magnetic reed relay, to a 
Teletype keyer. The reed relay can be used 
not only to key this AFSK generator, but 



standard FSK units as well. 

Simple circuits published previously 
have contained at least two transistors and 
a reasonable amount of other software. A 
look at the schematic. Fig, 1, shows this 
oscillator to have only one transistor and a 
minimum of other components. The actual 
audio shift is accomplished by switching an 
additional capacitance in parallel with the 
toroid to lower the tone on "mark." On 
"space," the switch is open and a higher 
tone (from less parallel capacitance) is 
generated. Although Cs and Cm are shown 
as one capacitor each, they are in reality 
several capacitors paralleled to give the 
desired resonant frequency. For such work, 
you cannot rely solely on the marked value 
of the capacitor. Tolerance variations can 
play havoc with combinations set up in 
(hat manner. Rather, true trial and error 
should be used to determine the values 
after the rest of the circuit is completed. 

For newcomers, the use of Lissajous 
Figures is the most practical method of 



002 mF 



88 mH 
toroid 



ftl 



J1 

Keyboard 



Cs 

0,02 mF 
(see text} 



0,01 mF 

-Hr- 



0.01 mF 



2N217 



J Cm 

032 mF 

1 see text) 








MIKE 

— » 




J3 - Mike 



— o 

AFSK 



Output 



r~ 



rh 



on/off 



-^r- 15V ro 'cell) 




J2 - Morse Key 



Fig. L Schematic of AFSK tone generator. 



JANUARY 1972 



35 







This is an overall view of the AFSK unit, showing 
front panel and interior circuitry, 

audio frequency determination. Briefly, 
setting up the circuit shown in Fig, 2 will 
allow frequency matching to within a small 
percentage. The source of the standard 
frequency will be investigated later. For 
the time being, such a standard is merely a 
known-to-be-accurate signal source. While 
observing the scope face, try various small 
capacitors of the approximate suggested 
values (or use a capacitor decade box if one 
is available) until a circle or ellipse appears 
on the screen. When that happens, the two 
audio sources are within one hertz of each 
other. 

Another method may be used for those 
lacking an oscilloscope, This technique, 
almost forgotten in amateur circles, is one 
using audio beats to match frequency. It 
permits matching to within one hertz, and 
gives a better result than Lissajous Figures 
for tones separated by several hertz. The 
audio beat method involves feeding the 
standard tone into a loudspeaker and the 





This is the Teletype patch (jack) panel with the 
reed relay assembly shown on the right end of 
the strip. The relay is enclosed in the coil t which 
is wrapped in masking tape. The unit is then 
attached to the printed circuit hoard referred to 
in the text 

AFSK generator to be calibrated into 
another (both through amplifiers, of 
course). As the generator frequency is 



adjusted to that of the standard, using trial 
capacitors or a decade box — as above — 
audio beats, that is, variations in ampli- 
tude ? will be heard. When the beat fre- 
quency is less than one or two per second, 
the two audio tones are matched within 
one hertz. 

Since exact frequency tolerance is not 
needed — it makes little difference to the 
receiving operator whether your "mark' 1 is 
2125,0 Hz or 2126.7 Hz - the audio beat 
method is perhaps better suited to the 
newcomer with only a limited audio refer- 




OSCILLOSCOPE 



WATCH FOR CIRCLE QR 
ELU?SE OH SCOPE FACE 



Af$K 
UNIT 



STANDARD 
SOURCE 



Fig. 2 r Simple frequency matching setup. 

■i 

ence source. At, say, five hertz separation 
between tones, the oscillographic Lissajous 
Figure will be a meaningless blur, while 
audio beats will be present at a rapid rate. 
Thus, adjusting the tones by the beat 
method, once slow beats are obtained, the 
frequency is within fair limits. 

Although much has been said so far 
about the "standard" frequency, details 

have not yet been given. Such a standard 
should be capable of supplying the mark 
frequency, 2125 Hz, and the space fre- 
quency, 2975 Hz, at a reasonable level of 
accuracy, stability, and sine waveform. 
Perhaps the easiest standard to use is 
another AFSK generator, known to be 
accurate. Such a generator could be bor- 
rowed from a friend or its signal used over 
a strong VHF link. Alternatively, a cali- 
brated audio generator could be set up for 
the 2125 Hz mark and 2975 Hz space 
tones. A third method is available to the 
ham who has an operating demodulator. 
Tune in a strong carrier on the receiver, as 
from the transmitter's spot function or the 
100 kHz crystal calibrator, and adjust the 
bfo to give the proper tones for Teletype. 
To calibrate the generator, adjust the 
standard to produce the tone for space 
(2975 Hz). Adjust Cs until the AFSK unit 
produces the correct space frequency, as 



36 



73 MAGAZINE 



measured by either of the frequency 
matching methods above. Close the switch 
grounding Cm and move the standard to 
the mark tone (2125 Hz), Adjust the value 
of Cm for the correct mark tone, Recheck 
the space tone to be sure interaction has 
not changed it. Feed the signal of the 
AFSK generator into the mike input of 
your transmitter, adjust the level control 
for 100% modulation, connect a key at J2 
or a mike at J3 (for the CW or phone 
identification required), and you are on the 
air. 

If you connect this directly to your 
keyboard contacts you may have some 
problems. First of all, the generator must 
be keyed "dry/* That is, there can be no 
current or voltage on the keying line. 
Second, the contacts used to key must be 
clean. While not so much of a problem 
with a keyboard, the rotating contacts of 
few T-Ds are clean enough to key this 
circuit without hash. The solution to these 
problems is to key through a set of 
contacts separate from the Teletype loop. 

For years, the only accomplished way 
to do this was by a polar relay. Other, 
spring-returned, mechanical relays differed 
too much in their make vs. break current 
to key without bias (changing the length of 
the 21 msec Teletype pulses). Recently, 
however, a new device — the magnetic reed 
relay — has come upon the scene. Litera- 
ture has described this device as being able 
to operate upwards of 2000 Hz, If a 2000 
Hz signal were fed to the activating coil, 
the contacts would make and break 4000 
times a second. Each actuation would be 
0,25 msec long. It appears, therefore, that 
the relay could operate on the 21 msec 
Teletype pulses. Such a relay was procured 
from a local supply house, and a coil 
wound on the form enclosed with the 





PRINTER KEYBOARD 


REPERF 




' D 














■ 


















Li 

4 


D LOCAl 

30P 

JPPLY 


Relay 


CtMl 












% 




\X> 


uu — 













Magnetic 
Reed Relay 
Contacts 



TO AFSK UNIT Ml) 



Fig. 3. AFSK keying arrangement installed in 
loop. 



relay. The coil has several thousands turns 
of 32-gage wire, and a dc resistance of 
45fi. It readily pulls in on 40 mA, thus the 
60 mA local loop current assures positive 
action. 

Transmitting tests using the relay to key 
the low frequency FSK rig showed no 
detectable bias. The relay was then instal- 
led into the loop as shown in Fig. 3. For 
mounting convenience it was fastened to a 
small printed circuit board, origin and 
original function unknown. The magnetic 
relay is now used for keying both the 
AFSK and FSK rigs, with excellent results. 

Construction techniques are. entirely up 
to the builder. At WA3AJR, the AFSK 
oscillator is built on a small piece of 
perf-board and mounted in a minibox with 
its complement of jacks and switches. The 
magnetic reed relay, as noted, is attached 
to a piece of printed circuit board for 
support, then mounted behind the Tele- 
type patch panel. 

The circuit shown here is, to me, a fast 
and easy way to transmit on VHF Tele- 
type. It is not recommended that the 
output of this particular AFSK generator 
be fed to a sideband transmitter to attempt 
low frequency FSK. The output of this 
circuit, while a reasonably good sine wave, 
is not perfect, and some spurious sideband 
generation may result. The relay keying 
circuit is applicable to all phases of Tele- 
type, and can be used in preference to a 
standard polar relay. If reversal of the 
tones or keying mode is desired — not 
necessary, but perhaps desirable in some 
cases — SPDT reed relays are available. The 
total elimination of a bias supply (needed 
with a polar relay) and the ability to 
separate receiver and transmitter from the 
same frequency and still maintain local 
copy are easily appreciated. 

Several modifications to this circuit are 
readily apparent. One amateur who built it 
added an extra transistor as a switch to 
further isolate the keyboard, instead of the 
relay. Another built the unit on a printed 
circuit board. Each, however, has retained 
the simplicity of the tone generation cir- 
cuit and discovered the fun in VHF Tele- 
type 

. . .WA3JR 



JANUARY 1972 



37 



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NAME 



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SAVE POSTAGE by remitting with order If paying in foreign currency, please add 10" Pennsylvania residents must add 6 fa*. 



7312 



Louis J. Hutton K7YZZ 
12235 S. E. 62nd Street 
Bellevue VIA 98004 




ndicatorsforSSTV Monitors 



For several years I have been experi- 
menting with SSTV and have realized 
that there is a need for a device to aid in 
tuning the SSTV signal to provide the 
correct audio output tones from an SSB 
receiver I've developed and tested tuning 
indicators for SSTV monitors in both 
solid-state and tube-type designs. The type 
used with tube model monitors incorpor- 
ates a 6FG6 light bar indicator, and a light 
emitting diode (LED) is used with solid- 
state designed monitors. 

Solid-state and tube-type SSTV moni- 
tors equipped with tuning indicators are 
shown in the photograph of Fig- 1. The 
monitor on the left is a tube-type based on 
the design by MaeDonald (QST, March 
1964). The light-bar tuning indicator is 
located just below the CRT screen. The 
monitor on the right of the photograph is a 
solid-state, magnetically deflected design 



based on a circuit by Make Tallent 
W6MXV. The LED tuning indicator is 
installed just below the vertical reset push- 
button. 









+ I50V 

TO 
+ 2SOV 



„ JN9J4 

®~H4 




6.3V 



Tube-Type Tuning Indicator 

The signal diode on the indicator input 
(point A of the schematic diagram) should 




Fig. I. Tuning indicators for SSTV monitors. 



JANUARY 1972 



39 




. 



B 
































Fig, 2. Tuning indicator displays. The no-signal state is shown in A. B shows presence of a steady 1,2 
kHz signal; C is a 15 Hz flickering to indicate that the SYNC signal is in tune. 



be connected to the high side of the SYNC 
gain control (Rl of the MacDonald cir- 
cuit). High voltage for the indicator is 
taken from the same voltage as that sup- 
plied for the 12AX7 limit er. With a 1200 
Hz test signal connected to the input of the 
monitor, of sufficient level to fully saturate 
the limiters, the gain control on the tuning 
indicator is adjusted until the two light 
bars in the display tube almost close. When 
a 1200 Hz SSTV SYNC signal is being 
received, the display on the 6FG6 tube will 
flicker at a 15 Hz rate. Maximum deflec- 
tion of the flickering display indicates that 
carrier reinsertion by the SSB receiver is at 
the proper frequency for optimum SSTV 
picture reception. Typical displays as seen 
on the tuning indicator are shown in Fig. 2, 
Figures 3 and 4 are photographs of the 



tube-type monitor showing the installation 
of the light-bar SSTV tuning indicator* The 
small circuit board just below the base of 
the tuning indicator tube is used to mount 
the gain control, bypass capacitor and 
rectifier. The remainder of the components 
are mounted on the tube socket. 



LED Tuning Indicator 

The components for this circuit were 
mounted on the piug-in circuit card con- 
taining the limiter and FM detector cir- 
cuits. The 88 mH toroid and associated 
parts for the tuning indicator circuit are 
shown in the photograph of Fig. 5. When 
the circuit assembly is finished, power is 
applied to the circuit and a 1200 Hz test 
signal is connected to the input at point B 








Fig. 3, Tuning indicators for SSTV monitors. 






40 



73 MAGAZINE 

















• 






Fig. 5. Tuning indicators for SSTV monitors. 




Fig, 6. SSTV LED tuning indicator for solid-state type monitors. 



JANUARY 1972 



41 



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LEE ELECTRONIC LABS, 88 Evans Street, Watertown, Mass. 02172 







Fig. 4- Tuning indicators for SSTV monitors. 



on the schematic (Fig. 6). The capacitor is 
selected to resonate the 88 mH inductor to 
1200 Hz by monitoring the output voltage 
developed across the diode load resistor 
with a VTVM. 

To install the LED tuning indicator in a 
solid-state monitor such as the model by 
W9LUO described in the March 1971 QST, 
connect input point B to the collector of 
transistor Q2. A 1200 Hz SSTV SYNC 
signal will cause the LED to flicker at the 
15 Hz rate. The indicator will be dark if 
the SYNC signal is absent. When the receiver 
is mistuned to the point that SSTV video 
or noise is appearing in the tuning indica- 
tor, the LED will flicker at a random rate. 

From a study of the schematic of the 
Model 70 Robot SSTV Monitor it looks 
like the input to the LED SSTV tuning 
indicator (point B) should be connected to 
pin number 6 of the integrated circuit Ul 
709C limited 



42 



73 MAGAZINE 



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R EPE ATER 

CIRCUITS 
MANUAL 



If you're into FM, you'll want to have 
this incredibly complete manual of FM 
circuits. You don't have your own repeat- 
er yet? Well, you've been thinking of 
it . , . admit it. Some fellows even have 
gone so far as to have a repeater in their 
car so they can extend the range of their 
hand units! 

This book, over 300 pages long, has 
just about every circuit that you could 
possibly want Many of these have been 
published elsewhere, but many haven't, 
too. And you can go out of your mind 
trying to find a circuit when you want 
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Call 



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$6-95 enclosed for FM Repeater Circuits 
Manual. 



Del C. Wininger WB6JNI 
7400 Tiptoe Lane 
San Jose CA 95129 

LETS REVISE 
The MORSE CODE 

Iv'e just read Ford's article of the same 
title in the November issue of 73 and it is 
wonderful, well thought out, logical and 
should be adopted immediately; also we 
should end poverty and war. In other words, 
no matter how good an idea is, if it involves 
something new or different it is a dirty 
communistic plot to violently overthrow the 
status quo. 

What we need is a system that will take 
the present equipment and make it work 
more efficiently. Now, although I could have 
thought of this all by myself, if given time, 
the credit should really go to some other 
guy. Let me explain. When I bought my 
TG34 code machine there were four tapes 
with it and one was a skip tape. A skip tape 
is one where every letter is sent at the 20 
wpm rate but there is about a four second 
pause between letters so the Novice can say, 
4 * What the hell was that?'* and have time to 
think about it before the next letter rushes 
at him. As Ford points out, code is an audio 
response phenomenon and letters sent slow- 
ly do not sound anything like letters sent 
fast. But it is just as easy to learn the fast 
letters as it is to learn the slow letters — in 
fact I think it is easier. 

Now hear this — here is the secret of the 
Morse code — free. To send code everyone 
should set his bug or IC keyer to the 20 
wpm speed. To send five wards per minute 
you pause between letters to allow time to 
think, and you wait longer between words 
for the person copying to take a breath and 
all this time he is learning what the 20 wpm 
letters sound like. Believe me, it is easier to 
receive with this system because the com- 
plete letter goes into your mind's shift 
register very rapidly and you have more time 
to search your memory before the next 
letter arrives It works; you will be astound- 
ed at the rapid progress you will make. Try 
it with the next Novice you work and see for 
yourself. . ♦ -WB6JNI 



44 



73 MAGAZINE 



Tom Yocom WAQZHT 
1530 Country Club Drive 
Marion I A 52302 



Identify your station 
Hie modern way, 

with a fully 

Hi 

automated CW 
in -age generated 
by an inexpensive 
solid-state 
matrix of cleverh 
placed diode; 



If you are a regular reader of 73 Maga- 
zine, you have undoubtedly noticed that 

a large number of articles have appeared 
covering the various aspects of amateur 2 
meter FM operation. The intent of these 
articles has been to entice you to give FM a 
try. Many people have been involuntarily 
bitten by the FM bug. I am no exception, I 
have found a large amount of personal 
satisfaction in designing and building digi- 
tal circuits for use in conjunction with a 2 
meter repeater; Through this endeavor I 
have been able to learn about several 
different fields: Touch-Tone, discrete com- 
ponents, and integrated circuits. 

Perhaps one of the more surprising 
things that happen when you start to 
investigate a new field is the large number 
of new techniques you are compelled to 
investigate and learn. My pursuit of control 
circuits for an FM repeater has lead me 
into several textbooks dealing with the 
subject of switching theory as it applies to 
the design of digital circuits. 

The repeater that f have been working 
on for the past 6 months consists of a large 
number of Sylvania TTL integrated circuits 
that were purchased on the surplus market 
at a cost of 10 cents per flatpack. 

There is more to building a device than 
removing the components from the original 
circuit board. 



JANUARY 1972 



45 



In digital design I have found that one 
frequently starts with a rather simple block 
diagram of the device desired and then 
proceeds to draw the detailed logic diagram 
consisting of the various nand and nor 
gates required to accomplish an objective. 
It is frequently useful to express some of 
the relationships mathematically using 
Boolean algebra. If you have mastered the 
subject you can then apply simplification 
rules to the equations to produce a less 
complicated statement of the problem. 
This is desirable because as you reduce the 
complication of the equation, you are in 
effect reducing the number of devices that 
will be required in the final circuit you 
construct. A simplified equation will lead 
to several benefits which come about as a 
result of less components: 

1 . Lower cost 

2. Decreased construction time 

3. Smaller area through less wiring and 
interconnection 

4. Increased reliability 

5. Simplified schematics 

6. Lower power consumption 

The September l c )7G issue of 73 de- 



CHARACTER 


DECIMAL 


COUNTER FLIP FLOPS 






STREAM COUNT 


■ 1 A 


FFB 


FF 


FF D 


• • E 


FF F 


1" 


hi jrik 


























— 


1 

















1 


1 


* 


2 














\ 





1 


• 


3 








o 







1 




Mant 


4 











1 








1 


• 


5 











1 


D 


i 


2 




e 











1 


1 


a 


2 


Wtfifc 


7 











1 




i 


3 


t*4* 


8 








I 











1 


* 


9 








V 








% 


2 


< 


10 


D 







Q 


1 





2 


— 


IT 





o 







1 




3 


bia 


12 


















2 


* 


\2 










1 







3 


— ■ 


14 








1 


1 


i 





3 


bldfik 


15 








1 


1 


i 


V 




— 


16 



















1 


— 


n 


D 


T 











1 


7 


<— 


18 





1 








1 







— 


\$ 













t 


1 


3 


— 


20 










1 










btti 


21 


D 


1 





1 





1 


3 


— 


22 





1 





1 


i 





3 


— 


23 





1 





1 


i 


1 


4 


* 




Q 


1 


\ 





a 





? 


* 


25 





1 


1 








1 


3 


blank 







1 


1 





i 





3 


* 


27 





; 


I 





i 


1 


4 


• 


28 





( 


1 


1 


o 





3 


■ 


29 





1 


1 


l 


D 


1 


4 


• 


30 





1 


1 


1 


1 





1 


i flunk 


31 


Q 


1 


1 


1 


1 


1 


& 


— 


32 


1 


'.I 


II 





D 





I 


til»> 


33 


1 


'1 











1 


2 




34 


1 











i 





2 


\r\k 




1 











1 


1 


3 


— 


36 


1 








1 








2 


• 


37 


1 








1 





1 


3 


Mi 


36 


1 








1 


1 




3 


l>Ufifc 


30 


T 








1 


1 


1 


4 



Fig. j, Basic count values and other data. 



scribed P. J. Ferrell's digital circuit that 
was used to automatically generate the CW 
identification for a repeater located in 
Seattle, Washington*. His call-letter gener- 
ator consists of a five-digit ripple counter 
which is used to control the characters 
generated. When you design the unit, you 
are basically saying things like this: 

i. I want a dot when the counter equals 
0. 

2. I want a dash when the counter 
equals 1 , 

3. I wan I a dash when the counter 
equals 2, 

4. I want a space when the counter 
equals 3, 

5. I want a dot when the counter equals 
4. 

6- I want a space when the counter 
equals 5. 

7. Etc. 

If you examine the above statements 
you will be able to see that what has been 
specified is the sequence dot dash dash 
blank dot dash . . . in terms of a sequential 
counter. The basic logic problem becomes 
one of specifying when the dots, dashes, 
and blanks are required as a function of the 
value existing in the counter. One way is to 
use a lot of gates or diodes to in effect say, 
"If the binary pattern in the counter is 1 1 
1 1 then I want a dash: if the binary 
pattern is 1 1 then I want a dot." 
This would imply that you would need a 
lot of gates with 5 inputs if you wanted to 
get the job done. When 1 was faced with 
this problem. I went to the textbooks and 
was glad to discover that someone else had 
already faced the problem and solved it for 
me! 

The original article suggested the use of 
a Karnaugh map for minimizing the num- 
ber of diodes required in the read-only 
diode memory. Karnaugh maps arc helpful 
in many instances, particularly when the 
number of variables is four or less. Many 
people find that when there are more than 
four variables the map becomes rather 
difficult to understand. Of course, the 
world does have map experts but what 
amateurs need is a simpler approach to the 

^Integrated Circuit CW ID Generator, PJ.I errcll 
73 Magazine. September 1970, p. 16. 



46 



73 MAGAZINE 



CLOCK 
PULSES 

V 



FF-A_ 
Q O 




TO OiOODIfiG GATES OR OlQDE READ ONLY MEMORY 

Fig, 2. Ripple counter described in text. 



problem 
coders. 



of simplification of counter de- 



The Tabular Method 

Several textbooks describe a method 
that requires a fair amount of clerical work 
but only a limited amount of real thinking. 
I chose to use that method. The discussion 
that follows is aimed at showing you how 
to apply the "Tabular Method" to simplify 
counter decoders. (An excellent discussion 
of the method, with some sophisticated 
extensions, exists in "Switching Circuits 
for Engineers," by Mitchell P. Marcus.) 

So that you can better understand the 
relevancy of the Tabular Method, let us 
analyze the decoding necessary for con- 
structing a digital CW code identifier 
having a 6-bit counter. Although most 
amateur calls can be described without 
resorting to more than 32 different charac- 
ters (dots, dashes, and blanks), let's gener- 
ate a fancy message. (Note that any mes- 
sage could be generated, e.g., RST 589 
IOWA Kj 

When the call is to be transmitted, your 
system will probably cause a push-to-talk 
relay to be activated. Consequently, it 
would be nice to begin the message with a 
blank to give the relay time to pull in. If 
the identifier is used in a complex system 
that supplies dial tone to its users, it may 
also be desirable to have a blank at the end 
so that the CW does not "run into" the dial 
tone. If you put these thoughts together, 
you will have a message that closely re- 
sembles the one described in Fig. i. 

Figure I contains additional informa- 
tion that will be referred to in different 
stages of our discussion of the simplifica- 
tion procedure. You should notice at this 
point that each character that composes 



tHe message has been paired with the value 
that would be in the counter when the 
character was to be generated. The value of 
the counter is shown in decimal and also in 
binary for your conversion convenience. 

The zeroes and ones in Fig. 1 represent 
the binary equivalent of the decimal num- 
bers shown in the "decimal count" col- 
umn. A zero means that the associated 
flip-flop is reset while a one means that the 
flip-flop is set. (Some manufacturers refer 
to the outputs as Q and Q, corresponding 
to true and false; Q = true = 1 and Q = false 
= OJ For convenience in referencing the 
flip-flops that compose the various stages 
of the counter, the flip-flops are designated 
as A, B, C, D, E, and F (See Fig. 1), If 
flip-flop A is in the set, or true, state, we 
wOl write the letter A; however, if flip-flop 



Original 
00000O 

000100* 
001000' 

000110" 
001100' 
1 0000 1 v 
100010^ 

00011V 
010101* 
011010* 
10001 V 

00111V 
10011V 

01111V 



Fig. 3. Values and reduction for blanks. 



New-A New-B 
000x00*" OOxxOO* 
0Ox00(K OOhxOO 

0001x0* 

00x100^ 

001x00' 

0001 1x* 
1000x1* 
10001x* 

00x111* 
x00111* 
100x11* 

0x1111* 



JANUARY 1972 



47 



1 


JJ 


■ 

000100 


c 

OOIOOO 


D 

OOOIIO 


E 
001100 


1 

F 
IOOOOI 


BLANKS 

G 

100010 


H 

OOOIII 


1 

oiotot 


ouoto 


K 

100011 


L 1 
001 III 


loom 


N 
01 MM 


OO01*0 




J 




y 






















000 Mx 








y 








y 














lOOOil 












7 




1 


, 


1 










IOOOU 














n/ 








y 








OOxlll 
















y 








y 






iOOIII 
















y 


1 








y 




100 x 1 1 






















y 






Oil II II 
























y 




y 


OOxxOO 


■J 


s/ 


V 




y 




















OIOIOI 


















y 












OIIOIO 




















y 











Fig, 4 
Tabular display for blanks. 



A is in the reset, or false, state, we will 
write A (read "A not"). Figure 2 shows the 
simple counter used in our discussion. 

You should notice that the binary ex- 
pression of the count shows that a 6-stage 
counter is being used. This means that you 
could have as many as 63 characters in the 
message (saving the last value of the coun- 
ter for stopping the sequence). The counter 
has 64 unique states, 000000 through 
111111. 

The Tabular Method can be used to help 
simplify logical states for various applica- 
tions but if we address our attention just to 
the CW identifier previously mentioned* 
then what we want in this case is a 
simplified statement of when we need dots 
and when we need blanks (the character 

generator circuitry produces dashes unless 
programmed to generate something else). 

The equations that result from the simplifi- 
cation can be used to specify the gates that 
must be used if you choose to decode the 
counter with integrated circuits, Since 
W7PUG's system used a read-only diode 
memory, I will address this discussion to 
that mode of implementation and show 
you how the Tabular Method will minimize 
the number of diodes required and produce 
a wiring map for use in constructing the 
decoder. For this example I chose a "fan- 
cy" message so that the counter would 
have to be composed of 6 stages rather 
than only 4 or 5* 



Since the circuitry generates dashes 
automatically, we have to generate expres- 
sions for only the dots and the blanks. The 
Tabular Method proceeds as follows: 
Expression for Blanks 

We begin by extracting from Fig. I the 
binary values of the counter corresponding 
to when we need to have blanks generated. 
This produces the list of values shown in 
Fig. 3. As the list is made, we arrange the 
values so that values with the same number 
of l's are grouped together. (The rightmost 
column in Fig. 1 is used to facilitate this 
listing*) The values are segmented with 
broken lines to show those numbers having 
no IX one 1, two Ts, etc. In the case of 
the blanks you see that there are six basic 
groups of values. 

The method now requires that each of 
the values in a particular group be com- 
pared to each value in the next group. In 
Fig. 3, this means that 000000 will be 
compared to 000100 and 001000:000100 
and 001000 will be compared to 0001 10, 
001100, 100001, and 1000 10. The com- 
parison operation consists of seeing if it is 
possible to derive the second number from 
the first number by changing only a single 
digit position. When 000000 is compared 
to 000100 you should see that you can get 
000100 from 000000 by changing the digit 
that is in the fourth position from the left- 
Consequently, these two values give rise to 
a new value written as 000x00 (The x 



48 



73 MAGAZINE 



shows the position that was changed to 
make the second valuej This new value is 
written into a new list shown in Fig. 3 as 
new-A. Comparing 000000 with 001000 
yields a new entry of 00x000 in list new-A. 

When a value is used in one of the 
comparing operations, and an entry is 
made in a new list, the original values are 
cheeked off. You will note that Fig, 3 
shows that all but two of the original 
values were used in this combining opera- 
tion. Each time a new group of numbers 
are used as "the first number/' a separating 
line is drawn in the new list. Additional 
new lists are made until no further com- 
binations can be made. Figure 3 shows the 
complete set of lists for the analysis of 
blanks. The values that do not combine are 
not checked but have been suffixed with 
an asterisk (*) to indicate that they are to 
be used in the next step of the simplifi- 
cation. 

When the comparisons have been com- 
pleted, a tabular display such as that shown 
in Fig, 4 is prepared. The column headings 
consist of the original counter values that 
were supposed to produce blanks, A row is 
added for each value that was suffixed with 
an asterisk when the comparisons were 
made. For each of the values shown to the 
left of a row, we now make an examination 
to determine the original terms which can 
be "generated" from the terms identifying 
the rows. The "generation" consists of 



Rule 1 



Rule 2 . . 



Rule 3 . 



A column, a, can be eliminated 
from the table if it has checks 
in every row that some other 
column, b, has checks, (The 
subset is saved J 

. A column, a, can be elimin- 
ated if it has checks in the 
same rows as another column, 
b, (Given two identical col- 
umns, one can be eliminated.) 

. . A row, z, can be eliminated if 
some other row, y, has checks 
in every column that z has, 
AND the number of 0's and 
l's in z is equal to or greater 
than the number of 0*s and 
l'siny. 

Fig. 5. Simplification rules. 



replacing the x or x's with both and 1 
and then checking off the original terms 
created. For example, if we take the first 
row, with 000 1 xO we can generate 000 1 00 
by substituting for x and we can genenile 
0001 10 by substituting 1 for x. 

We now place check marks beneath the 
original terms generated; 000100 and 
000110. Applying the same process to an 
entry such as OOxxOO would produce these 
original terms: 000000, 001000, 000100, 





A 

oooooc 


e 

OOOKX) 


c 

OOHDOO 


D 

OOOIJO 


E 

OOI IOO 


1 F 
IOOOOI 


BLANKS 
6 

1000(0 


H 

OOOIII 


1 

OJOtOl 


OMOIO 


K 
IOOOM 


[ L 
OOlltl 


M 
IOO 111 


N 

ON HI 


OOOIxO 




y 




y 






















OOOIIx 








Y 








y 














lOOOxl 












y 








■ 


y 








IOOOIk 














y 








y. 








OOxl If 








L 








y 








.....y 






xOOlll 






\ 










y 










y 




lOOx II 




1 
: 


J 
















y 




y 




OmMII 
























y 




y 


OOxxOO 


y 


V 


V 




V 




















OIOIOI 


















y 












ouoio 


















y 











Fig. 6. Tabular display for blanks after applica- 
tion of reduction rules. 



JANUARY 1972 



49 



- 



Rule 1 
and K 
Rule 1 



can be 
thereby 
can be 



and 001100. The columns corresponding. 
to each of these original values has a check 
mark opposite OOxxOO. If the term con- 
tains no x r s, for example 01 1010, then you 
place a check mark in only one column. 
When all of the check marks are in place, 
the table is ready to be simplified by the 
application of a few simple rules. Figure 4 
shows the table with all of the check marks 
entered properly. 

Figure 5 lists the rules that are applied 
to the table to perform the actual reduc- 
tion. Let's apply these rules to Fig. 4 and 
produce the slightly modified form shown 
in Fig. 6. 

For ease of identification, the columns 
in Figs. 4 and 6 have been labeled with 
letters of the alphabet. Rule 1 can be 
applied to columns L and N thereby 
eliminating column L. 
applied to columns G 

eliminating column K. 
applied to columns A and B, thus elimina- 
ting column B. Rule 2 can be applied to 
columns A, E and C, thereby eliminating 
columns C and E. 

Figure 6 shows with shading the col- 
umns that have been removed from the 
table, The object of this last step is 
hopefully to eliminate rows in the table. In 
this particular case, no rows were elimin- 
ated. Had rows been eliminated, the cor- 
responding terms would be dropped during 
the next step of our simplification. 

The final step in the simplification is to 
write a statement for the quantity of 
interest. This simplification was for blanks 
so we will write a statement which com- 
bines the terms opposite rows that were 
not eliminated from the table. The result 
that we get is as follows: 

BLANKS = 001x0 or 0001 I x or 
1000x1 or lOOOlx dr 00x111 orxOOlll 
or 0x1111 or OOxxOO or 010101 or 
011010 

You should recall that the binary values 
correspond to the state of the flip-flops A, 
B, C, D, E, and F. We can thus rewrite the 
statement by replacing the 0's and l's with 
the appropriate flip-flop designator and 
simply dropping the X%. Doing this, 
000 1 xO becomes ABCDF, The resulting 
equation for blanks is thus: 



New-A 
000010 00001 x* 



000011 
000101 
001001 
011000 

001101 
011001 
011100 
100101 

011011 
011101 
011110 



00x101* 
X00101* 
001x01 
0x1001 

onoox 

011x00 

0x1101 

0110x1* 

011x01 

omox 

0111x0* 



New-B 

0x1x01* 
0x1x01 
011x0x* 
011x0x 



Fig. 7 \ Values and reduction for dots. 



BLANKS = ABCDF or ABCDE or 



ABCDF_or ABCDE or ABDEF or BC DEF 
or ABCEF or ACDEF or ABEF or 
ABCDEF or ABCDEF 

In order to implement this equation, 
one diode will be required for each of the 
or^s for a total of 10 diodes. For each of 
the terms in the equation, there will be one 
diode per flip-flop named. Thus ABCDF 
will require the use of 5 diodes. There will 
thus be 56 diodes for the terms and 10 for 
the ar's for a total of 66 diodes. If we had 
not simplified, there would have been one 
diode for each value of the counter (14) 
plus 6 Hiodes for each value (6 x 14 - 84) 
or a total of 84+14-98 diodes. 
Application of the Tabular Method has 
thus reduced the number of diodes by 
approximately 30% - a 30% savings in parts 
and wiring! The savings that you will 
realize varies with the complexity of the 
message. 

Expression for Dots 

To be sure that you understand the 
simplification method, let's apply the tech- 
nique to the values for dots. 

Figure 7 shows the binary values that 
have been removed from Fig. 1 and listed 
in groups based upon the number of 1 's in 
the values. You will notice that this time 
we have only 4 groups of values. As in the 



50 



73 MAGAZINE 





A 

ooooto 


B C 

00001 j 000101 




00 IO0I 


I E 
01 1000 


DOTS 
F 1 G 

001 101 OIIOOI 


H 
OIIIOO 


1 

100101 


J 
OIIOII 


K 
01 1 101 


L 
01 1 1 10 


0000 Ix 


V 


n/ 






















* 00*101 






v/. 






n/ 






1 








xooroi 




1 


■J 












V 








0110x1 














s/ 






n/ 






0111x0 
















v/ 








y 


OxIxO) 








V 




y 


s/ 








V 




OlIxOx 










v/ 




• 


s/ 






V 





•ROW HAS 0CEN ELIMINATED BY 
APPLICATK>N OF RULES 



Fig. 8. Tabular display for dots. 



previous example, the simplification begins 
by comparing 000010 to 000011. This 
comparison yields the entry 0000 Ix in the 
second table. None of the remaining values 
in the second group can be derived from 
000010 by changing only a single digit. 
The simplification continues by comparing 
aH of the values in the second group to the 
values in the third group. These compar- 
isons generate the new values 00x101, 
xOOlOl , etc. In this case, by the time all of 
the group comparisons have been made, all 
of the original values have been used at 
least once and are therefore suffixed with a 
check mark. The values in the new table 
(new-A in Fig. 7) are then compared and 
used to generate new values when possible. 
You should note that when values invol- 
ving x's are compared, it is necessary that 
the two values contain x's in the same 
positions before you check to see if the 
second value can be derived from the first 
value by changing a single zero or one. 
Figure 7 shows that the final result consists 
of 7 terms with asterisks. The next step is 
to construct the tabular display of the 
original values and the asterisked values 
derived from the comparisons. Figure 8 
shows such a table. 

The next step is to place a check mark 
in the column or columns corresponding to 
the original values that can be derived from 
the asterisked terms. Figure 8 shows the 
completed table. Once again we must now 
apply the three rules shown in Fig. 5 to 
check marks in the tabular display- 
Rule 1 can be applied to columns C and 
I thereby eliminating column C. Rule 1 can 



be applied to columns D and F thereby 
eliminating column F. Rule 1 can be 
applied to columns E, G, H, and K thereby 
eliminating columns G, H, and K. Finally, 
rule 2 can be applied to columns A and B 
thereby eliminating column A. We can now 
write a statement for dots in terms of the 
asterisked terms that still have at least 1 
check mark in their row. The statement is: 

DOTS = 0000 Ix or xOOlOl or 0110x1 
or 01 1 1 xO or Oxl xO I or 01 IxOx 

The statement is next written in terms 
of the flip-flop designators previously de- 
fined (A, B, C,. : . ... ). 

J30TS^ ABCDE or BCDE"F or ABCDF 
or A BCD F or ACEF or ABCE 

As in the case for the blanks, one diode 
will be required for each term to be ored 





WITHOUT 
SIMPLIFICATION 


WITH 

SIMPLIFICATION ' REDUCTION 


BLANKS 


98 


66 


30% 


DOTS 


84 


34 60% 


TOTAL 


182 


100 45% 

. 



Fig, 9, Diode count. 

plus one diode will be required for each 
flip-flop mentioned in each term. The 
decoding for the dots will therefore require 
6 + 28 = 34 diodes. Without simplification, 
the decoding would have required 84 di- 
odes (12 + 72). Notice again that the 





FF A 


FF B 


FF C 


FFD 


FFE 


FF F 


00001 X 














1 


X 


X00TO1 


X 








1 





1 


onoxr 





1 


1 





X 


I 


0111x0 





1 


1 


1 


X 





0X1X01 





X 


1 


X 





1 


01 IXOX 





1 


1 


X 





X 



Fig. 1 0. Wiring map for do ts 



JANUARY 1972 



51 



FF-A FF-B FF-C FF-0 FF-E FF-F 

QQ QQ 0Q QQ 




Fig. 11, Wiring map for blanks. 



simpliciation has been well worth the 
effort ! 

If we take a look at the total problem 
we see that simplification has been very 
worthwhile. Figure 9 shows the diode 
count with and without simplification. 

To complete our discussion, let us ad- 
dress ourselves to the proper interpretation 
of the equations as they apply to the actual 
wiring of the read-only diode memory. It is 
helpful to construct a tk map" that will help 
you find your way around the wiring 
details. 

Figure 10 is the wiring map for dots. 
Across the top of the map you will see the 
flip-flop designators. The various rows cor- 
respond to the individual terms that are in 
the reduced equation. Take an equation 
such as: 

DOTS = OOOOlx or xOOlOl or 0110x1 
or 1 1 1 xO or x 1 xO 1 or 1 1 xO x 

For each of the terms, enter one row 
into the map. The 0*s represent a diode 
connected to the false output of the 



flip-flop while the l's represent a diode 
connected to the true output of the flip- 
flop. Where there are X's, no diodes are 
required. The map can thus be described 
by simply displaying the terms of the 
equation in a list! Such a wiring map is 
useful when you start to construct your 
decoder. Figure 1 1 shows the map with the 
diode wiring schematic superimposed to 
help you see the map's usefulness for 
wiring the blanks decoder. 

In this discussion I have introduced you 
to a method of simplification that is not 
difficult and yet is flexible enough to allow 
easy simplification of count registers 
having many digits. 

As a final testament to the method's 
utility ? J have applied the principles de- 
scribed herein to my 5 -digit counter and 
have an identifier running that flawlessly 
generates my call! Why not build yourself 
an identifier? You might include several 
decoders to generate signal reports, ARRL 
section, etc. for field day use! 

. . .WA0ZHT 



*J j—. 



73 MAGAZINE 



CIRCUITS, CIRCUITS, CIRCUITS. 

The following circuits have appeared in the referenced books, magazines, application notes, etc. 
While we try to reproduce alt of the information that should be needed by an experienced constructor, 
readers may want to avail themselves of the original sources for peace of mind. 

Readers are requested to pass along any interesting circuits that they discover in sources other than 
U.S. ham magazines* Circuits should be oriented toward amateur radio and experimentation rather 
than industrial or computer technology. Submit circuit with all parts values on it, a very brief 
explanation of the circuit and any additional parts information required, give the source and a note of 
permission to reprint from the copyright holder, if any t and the reward for a published circuit will be a 
choice of a 73 book. Send your circuits to 73 Circuits Page t 73 Magazine, Peterborough NH 03458. 




ie'-V r 



Capacity Meter. From Dec. 60 73 pi 5. L1-C2 and 
L2-C4 should tune to the same frequency, around 
1450 kHz. Calibrate by setting C4 near max and 
mark that "zero." Peak meter with C2 t which is 
zero adjustment. Calibrate with known capacities 
and mark C4 dial 




VK2AAR Wire Antenna 
Works best on 20m t with higher (but not unreason- 
able) swr on 40 & 80m £3:1). Note bottom section 
drags sides in about 15 , a critical dimension that 
may require experimenting. Antenna courtesy 
Amateur Radio July 71, Wireless Institute of 
Australia, Box 36 f East Melbourne f Vic. 3002. 



AX. 

INPUT 




-9V 



ORET 



From 73 Magazine, November I960, this schematic gives the basics for a simple, inexpensive audio 
frequency meter. For the cheapie special version, omit all switches and components associated with 
them. Connect a capacitor of proper value in place of SIA. Ranges are: OFF, 30 kHz, 10 kHz, 3 kHz, 
1 kHz, and 300 Hz, Meter is 0-1 mA. 





JANUARY 1972 



53 



EXTERNAL 
ANTENNA 



LI 



V 







1 
1 



^js365 pF 



EXTERNAL 
GROUND 



HEP B02 



m 



SIGNAL 
DIODE 






1 



= OlyF 



4 7K 



I MEG 




ff SPEAKER + 
M 45a. 



PNP 

POWER 

TRANSISTOR 



12 
VDC 



DSC 
VOOOJ BOTTOM 

x^y view 

HEP 80£ 



LI -FERRITE ANTENNA COIL (VARIABLE) 



Three transistor radio (AM). Adjust R4 so voltage across speaker is 1/2 supply voltage. Works 
surprisingly well. Circuit courtesy Calectro Handbook. LI is a ferrite antenna coil (variable) (Calectro 
#D2 -84 1 ); Q2 is an NPN transistor (Calectro #K4-SQ6); Q3 is a power PNP (Calectro #K4-521); Dl is 
a signal diode (Calectro WA 1-227). 




KEY 



3 VDC 



SP1 



SPI-45^! 4 In. INTERCOM 
SPEAKER 

ICI-HEP570 




HAMMOND 

SUE 

SWITCHING 

TORQID 



5 
6 



CI 
lilF 
"50 V 
Non Polar 



R2 

44ji_ 
5W 



I 



T2 



O- 




vieR 

XFMR 



Code practice oscillator using one IC t loud. Inter- 
com speaker may be replaced with a regular 4—8^1 
speaker if a transformer is used to match the 
impedance down from 50l2 to 4fZ Circuit is from 
Motorola HMA-36, Radio Amateur's IC Projects, 
available free from Motorola r Dept 73, Box 
20924, Phoenix AZ 85034. 



A transistor power supply for a vibrator-powered 
mobile rig. Called a "Plug-In Solid-State Vibrator 
Eliminator' 1 by its designer, Vera Epp t it First 
appeared in FM Magazine, and is reprinted from 
The Best of l 7 M, available from Radio Bookshop, 
Peterborough NH 03458, for $4.95. 



w 



LI 



8.22 jiH Tl 

(S«t Ttxt) 



CI 

91- 




250 pF 



VIA 
1/2 6U8 



1:3,6 




YJ 
]350Q 

k 



R5 
220K 



VIB 
1/2 6U6 



£R4 8 

JlOOK <fc_ 



1 



X 



C5 
.05 



VI 



4 5 



■O +I30-25OV 



TO RECEIVER 



-O 6,3 VAC 



-O GROUND 



VLF converter, tuning 10 to 30 kHz. I-f is at the low end of the 80 meter band. From an article in 13 
Magazine, July 1961. 



54 



73 MAGAZINE 



LI 



CI 



Hf-Z 
INPUT 




yvwx 



2.7 mH 




) 



TO HIGH END 
VFO OSC COIL 



2.2-3.3 pF 

VCI 

6,8 SC 20 



This varactor modulator will put your vfo-operated 
AM transmitter on FM in ten minutes, Assemble it 
on a standard three-terminal phenolic tiestrip and 
tuck it into a corner of your chassis. Both this 
modification and the one below for crystal con- 
trolled rigs should be driven with a high output, 
high impedance crystal or ceramic mike. 



+ 9VO 



RETUENO 



Rl 
IOK 



I 



SJ 



R2 
IK 



R3 

33_n_ 

3W 



01 



H=V NO 47 



Interrupted-Power Indicator. Circuit courtesy Mo- 
torola Semiconductor Power Circuits Manual. 



» voc 



+ 14 v cc 



Hl-Z 
INPUT 




CZ 

if 



2ZO pF 
DISK 



VCI 



SHORT 
LEADS 
TO 
XTAL 



r 



Use this device to put your crystal-controlled AM 
rig on FM, Both this schematic and the one above 
are from the 73 Inc. hook, The Best of FM, 
reprints from the now defunct FM Magazine. 



IN 




8jv 

SPKR 



V + 



ft? 

One watt audio amplifier using one IC For a gain 
of 10 leave pins 2 & 4 open and ac ground pin 5 
with the 10 jUF capacitor. For a gain of 18 leave 
pins 2 & 5 open and ac ground pin 4, A gain of 36 
will be obtained if you pin 2 to pin 5 and ac 
ground pin 4, Circuit courtesy Motorola Semicon- 
ductor Power Circuits Handbook. 




AUDIO 



10,7 MHz limiting amplifier, using the Motorola MFC601Q, a monolithic silicon IC especially designed 
for 10*7 MHz i-f applications. Typical application schematic courtesy of Motorola Functional Circuits 
product bulletin. 



JANUARY 1972 



55 



Making Your Ads Pay 

While the larger manufacturers have the budget to pay an ad agency the $100 
or so it costs to make up a page ad for a ham magazine, most smaller companies 
find this prohibitive and wonder what they can do to get the job done for less. 

We make up ads for about half of our advertisers and it costs them very little 
for this extra service. We go that extra mile to make 73 a better advertising 
medium, 

STEP ONE. Throw the engineers out of the art department and keep them 
out Sit yourself down in the chair of a user of your product and make a list of 
the many ways in which your product provides advantages to the user. * .the 
user, not the engineer. The engineer thinks in terms of the bandwidth of a 
receiver, the user in terms of only one signal coming through the receiver. What 
are the benefits, not what are the specs. Oh, you can list the specs too, but these 
are NOT the selling points, 

STEP TWO. In laying out the ad you should keep in mind that you need some 
sort of "grabber" to make sure that your ad, once seen, is actually read. VW 
does this with a big picture and a clever caption. Perhaps a picture will do it for 
you. Or maybe you can think up a good one-liner. Every ad in 73 is seen by 
every reader, but many go unread because they don't grab attention. Your ad is 
wasted if it isn't read, obviously. 

Work your selling points into the copy and don't be afraid of running all the 
copy you need to get your point across. Once you have the attention of the 
reader you want to be sure that he understands why he cannot go another week 
without buying your unit, why he will have so much fun with it is worth all the 
problems he may have in getting it by the wife. 

A professional picture of the. product is extremely important. You're going to 
need that for spec sheets, brochures, etc., so you should get a good commercial 
photographer to do the job right for you. We can, if you are short of time, shoot 
a workable picture with our giant copy camera, but we don't have the facilities 
to do much more than a good front panel shot. 

STEP THREE, Send a sketch of your ad along with the typewritten copy to 
73. Include the photograph and any ink drawings or special artwork for the 
company name, cartoons, etc. This is due in our hands before the tenth of the 
month if it is to be sure and make the next published issue. 

STEP FOUR. In a few days you will receive proofs of your ad as set up by the 
73 Art Department Make sure that everything is as you want it. Make changes 
sparingly at this time as there will be no further opportunity for checking a 
proof before publication, 

STEP FIVE. As soon as the magazine is out with your ad in it you will receive 
a copy by first class mail. A few days later the orders will start coming in and 
then your problem is keeping up with business. 

And what will your ad cost you to make? Most full page ads can be made up 
for less that $50, if there aren't too many pictures or reams of real small type. 
Our business is selling advertising and magazines, not making up ads. We charge 
only our costs on ad makeup, so there is no way to get an ad made up more 
reasonably unless you have the typesetting^ headliner, artists, and photo lab 
needed available. 

Send your ads to Aline Coutu, 73 Magazine, Peterborough, N.H. 03458 and 
get ready to start filling orders. 



56 



73 MAGAZINE 



The Makings 
ofa 

Modern Day Receiver 



W, Edmund Hood W2FEZ 
223 Pullman Ave. 
Rochester NY 14615 



There was once a time — and when I 
first became a ham there were still a 
few oldtimers who could remember it — 
when the ham radio operator was, in fact 
as well as in name, an amateur of radio. His 
station was more than a mere investment 
of dollars and cents. It was the testimony 
of his skill, Rather than take the coward *s 
way out, those hardy hams of yore built 
their rigs — from the ground up. 

It*s possible that I'm being a trifle 
unjust. Equipment has, since then, become 
far more complex, and construction tech- 
niques today require a costly array of tools 
and test equipment. Nonetheless, I feel 
that a ham isn't truly an amateur of radio 
unless he at least knows what's happening 
inside his rig. To the ham whose daily 
bread is earned in the electronics trade, 
such knowledge is a reality; but to the rest 
of the amateur world a twentieth-century 
receiver is nothing less than a magic box of 
mystery. 

Now, it's a pretty safe assumption that 
even the Novice understands the operation 
of a basic superheterodyne. But what 
about the expensive complicated receivers 



now being advertised for the ham of 
today? Triple conversion, synthesizers, 
tuned i-f, product detectors, and other 

terrifying names go round and round in the 

■i 

head of a poor Novice struggling to com- 
prehend the wiles and windings of the 
engineering marvel he just went hopelessly 
into debt to acquire. Oh, for the good old 
days when a guy could sit down and build 
an oscillator, an amplifier, or a mixer and 
not bother himself with such complexity. 

Frankly, today's receiver still uses the 
same principles developed back in the dark 
ages when the ARRL vehemently objected 
to the use of the "new" superheterodyne. 
The block diagram shows a typical scheme 
of the up-to-date receiver. At first glance, it 
looks a little frightening, but it really isn't 
that bad if you just take one part at a time. 

To most homebrew artists, there *s noth- 
ing really too mysterious about a crystal- 
controlled converter, in which a whole 
band is converted to a range that can be 
covered more readily by whatever receiver 
may be available. Looking at the first part 
of the block diagram of the receiver, we 



JANUARY 1972 



57 



find a broadband rf amplifier and mixer. If 
we ignore the fact that the local signal is 
coming from a synthesizer, and imagine it 
to be the output of a crystal oscillator, we 
have a block diagram of a typical crystal- 
controlled converter. 

Taking a look now at the remainder of 
the receiver, except for the synthesizer, we 
have a dual-conversion receiver covering 
9.0 to 9,5 MHz, The purpose of dual 
conversion is to combine the advantages of 
a high i-f with those of a low i-f. When a 
high i-f is used, image signal frequencies are 
so far removed from the desired signal 
frequency they are eliminated altogether. 
The disadvantage of a high i-f is that high 
selectivity is much more difficult to 
achieve. Bandwidth is a direct function of 
Q and frequency. If the Q of a tuned 
circuit is held constant while its frequency 
is varied, the bandwidth will be narrowest 
at the lowest frequency. For a really 
selective receiver, a low i-f is required. 
However, when the i-f is low, it is harder to 
reject image signals because they are closer 
to the desired signal. 

The answer is two conversions. The first 
uses a high i-f, which gets rid of images. 
The first i-f passes through a tuned stage, 
then it enters a second mixer, where the 
heterodyne process is repeated all over 
again. In this case, when the incoming 
signal is of one frequency, and one fre- 
quency only, the local oscillator can be 
crystal controlled. The new i-f is only 240 
kHz. (Some commercially built receivers 
went as low as 50 kHz,) At a frequency as 
low as this, a couple of tuned stages can 
give a bandwidth as low as 3 kHz (or less), 
Commercial receivers sometimes have the 
final i-f stages deliberately loaded to open 



w 



RF 
AMP 



MIXER 



455 
MH2 



DETECTOR AUDIO 




I I-F AMP 

L459 MHz 




OSCILLATOR 



A BAND OF COMBINE WITH 
SIGNALS THE LOCAL SIGNAL 
HERE HERE 



TO PRODUCE A RANGE OF 
FREQUENCIES THAT CAN BE 
TUNED BY THIS RECEIVER. 



V 



BROADBAND 

RF AMP MIXER 





LOCAL 

SIGNAL 



THIS SIGNAL USUALLY COMES 
FROM A CRYSTAL OSCILLATOR. 

IF IT CAME FROM A SYNTHESIZER, 

IT WOULD NOT MIX ANY DIFFERENTLY. 



Fig. I. A basic superheterodyne receiver block 
diagram. 



Fig. 2. Basic theory of a crystal -con trolled conver- 
ter. Nothing new to the ham — especially the mo- 
bile enthusiast 

up the bandwidth, then they insert a 
crystal or mechanical filter to give the 
bandwidth the desired shape. 

Having explained the purpose and 
theory of double conversion, let us turn 
our attention back to the mixers. Nowa- 
days, the best mixers are exactly the same 
thing as the balanced modulators used in 
SSB work. In fact, they are modulators and 
always have been. The advantage of using 
an SSB modulator is that it gets rid of the 
two original frequencies entirely, hence a 
quieter, more efficient mixer. Many of the 
commercial receivers that use vacuum 
tubes (and quite a few do) use the type 
7360 beam-switching pentode as a mixer. 

Some of the better solid-state receivers 
use a diode-bridge-balanced modulator for 
their mixers. The input transformer for 
such a mixer is very critical, however, if the 
best results are to be realized, so the ham 
who isn't too pj md to use tubes will find 
the 7360 can't be outdone, 

While we're on the subject of mixers 
and balanced modulators, it is a good time 
to mention a related circuit, the product 
detector, A product detector is exactly the 
same as a mixer or frequency converter 
circuit, except that the output is audio, 
rather than rf . The principle is the same as 
has long been used wherever a bfo signal is 
mixed with an incoming CW or SSB signal 
to produce audio. The difference is that 
the product detector gives no output at all 
unless both the i-f and the local signal are 
present. Here again, balanced modulator 



58 



73 MAGAZINE 



kHz 



I- START WITH A CRYSTAL OSCILLATOR 
GENERATING A SINGLE FREQUENCY. 



X7 



X2 



fl 




1.4 MHz 



2. MULTIPLY IT AM} RASS THE RESULT THROUGH 
A SERIES CRYSTAL TO CLEAN IT UP. 




I m 



SPECTRUM 
GENERATOR 



X9 



czi 



3, GO 8ACK TO THE ORIGINAL SIGNAL; 
MULTIPLY IT, AND BREAK THE 
RESULTANT INTO A SPECTRUM, 



SELECTIVE 
AMPLIFIER 



SPECTRUM 
GENERATOR 



X3 



AMY MULTIPLE OF 50O kHz 
mm FIRST MIXER 




4. SELECT THE INDIVIDUAL 
HARMONIC YOU DESIRE. 



THAT IS ALL THERE IS TO A SYNTHESIZER; 

A SINGLE CRYSTAL CONTROLLING MANY FREQUENCIES, 



1400 KHz 

FOR THIRD MIXER 



SPECTRUM 
GENERATOR 



A VERY BASIC SYNTHESIZER 




Fig, 3. A very basic synthesizer. 



circuits are superior to pentagrid or triode 
mixers and their solid-state counterparts, 
since only audio is present in the output. 
(A pentagrid mixer product detector would 
have the two if carriers present in the 
output, which could produce a little distor- 
tion or noise,) 

Going back to the mixers, in the original 
superheterodyne circuit, the local signal 
came from a vfo. In dual-conversion re- 
ceivers, a crystal oscillator is used- In the 
more sophisticated receiver, they use a 
synthesizer* 

A synthesizer is a device that produces a 
signal at a frequency different from the 
input signal or signals. A frequency .doubler 
is a simple form of a synthesizer; a mixer is 
another. Modern receivers use a synthesizer 
to produce the several frequencies required 
for the various conversions involved, all 
being produced from the output of a single 
crystal oscillator. That way, if the crystal 
should drift slightly, all conversion fre- 
quencies in the receiver would drift at the 
same time, and by the same percentage. 



The receiver, then, would continue to hold 
its calibration. The receiver discussed in 
this article uses a relatively simple synthe- 
sizer, A 1 00 kHz crystal is multiplied up to 
1400 kHz in a basic frequency multiplier. 




Fig, 4. A diode-bridge-balanced modulator used as 
a mixer. 

The 1400 kHz signal passes through a series 
crystal and a tuned amplifier after which it 
is injected into the mixer for the final 
conversion. The original 100 kHz is also 
multiplied to 500 kHz and fed into a 
spectrum generator (the fancy name for a 
crystal calibrator). The spectrum, which 
consists of all multiples of 500 kHz, feeds 
into a selector, which isolates the desired 



JANUARY 1972 



59 




CRYSTAL BARGAINS 



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We can supply crystals 
from 16 KHz to 80 MHz in 
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Over 6 million crystals in 
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mail add 15C per crystal 
— for airmail, add 200 per 
crystal. Inquire about 
special quantity prices. 



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Florida 33901 

(813) 936-2337 

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Any CB crystal, trans, or rec. 

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Any amateur band crystal in FT-243 holders 

(except 00 — 160 meters) 

4 
00 meter crystals in FT-243 holders 



2.50 



for 



multiple of 500 kHz, passes it through a 
crystal filter, amplifies it, and uses it as the 
local signal for the crystal-controlled con- 
verter (the first conversion). 

By using exact multiples of 500 kHz for 
the first conversion, the receiver can select 
any frequency range 0,5 MHz wide, and 
convert to the range of the tunable portion 
9.0 to 9*5 MHz, Since the tunable portion 
always tunes over the same frequencies, the 
receiver has the same bandspread regardless 
of the band of incoming frequencies. 



a 



i-f m 




Fig. 5. A mixer circuit with audio output is a pro- 
duct detector. 



(Some fancy mechanical manipulation by 
National engineers provided a dial that 
always have a 1 kHz per division calibra- 
tion. The famous HRO 500 uses a spec- 
trum conversion scheme very similar to the 
one Fve described.) 

Suddenly , now, the whole puzzle seems 
to fall together. Incoming signals are mixed 
with selected frequencies to convert them 
to the range of 9.0 to 9.5 MHz, This range 
is then tuned by a dual-conversion, 9,0 to 
9,5 MHz receiver. The first and the third 
conversion come from the same 100 kHz 
crystal, while a stable vfo tunes the second 
conversion. Image rejection is achieved in 
the second conversion, which uses the 
1640 kHz i-f, and selectivity is obtained in 
the final 240 kHz i-f. The receiver is a 
complex conglomeration of mixers, ampli- 
fiers, oscillators, doublers, and spectrum 
generator, but each part is, in itself, basic. 

Several years ago, when financial adver- 
sity deprived me of a station receiver, and 
prevented my buying another, I decided to 
build one. Being employed, at the time, by 
National, I was immediately deluged with 
suggestions and the monster I have just 
described evolved. I chose to build it using 
tubes, rather than solid-state, simply be- 
cause tubes are easier to scrounge. As time 
passed, my interest waned. Over the past 
couple of years, it has spent much more 
time on the shelf than on the bench. 

Better times have come, now, and my 
interest in ham radio has gradually revived. 
I could easily go out and buy a receiver to 
get back on the air, but there is something 
about this project that bears a certain 
fascination. Perhaps I am a throwback, 
enslaved by my own stubborn pride. All I 
know is that I feel I must earn my place in 
the airwaves by producing that which gets 
me there. At any rate, come what may, I 
have completed my receiver, long ago 
humorously nicknamed the HRO .007 by a 
wisecracking National engineer and, so far, 
it works. With just the front end to go, I 
am determined that, by the time this 
article sees printer's ink, 111 be on the air 
once more, and 111 be one of the few hams 
of today who can truthfully say, "I made it 
myself/* 

.W2FEZ" 



• » 



60 



73 MAGAZINE 



John Schultz, W2EEY/DL 



SIMULTANEOUS 
MULTI-BAND TRANSMISSIONS 

Simultaneous transmission on two or more bands has 
various technical advantages, and is allowed by the FCC 
under certain conditions. This article illustrates primarily 
simple combiner networks which will allow simultaneously 
the operation of two transmitters on different bands into 
one multihand antenna without transmitter interaction. 



Simultaneous transmission of the same 
modulated signal on two or more amateur 
bands is permitted by the FCC under 
certain circumstances as discussed later. 
Such simultaneous transmission has various 
advantages in increasing the dependability 
of reception if a separate receiver is used 
on at least two of the transmitted 
frequencies and also an advantage in 
permitting reception on different single 
band receivers. The simultaneous transmis- 
sion technique is often employed by 
shortwave broadcasters, commercial traffic 
stations, etc. Usually a separate transmitter 
and antenna is used for each band. 
However, for the amateur situation where 
multiband antennas are available and space 
for antennas restricted, it would be advant- 
ageous to have two transmitters operating 
on different bands coupled to one antenna 
for simultaneous operation. The networks 
which permit the use of transmitters in this 
manner are called "combiners." Many 
elaborate forms of such networks have 
been developed for commercial applica- 
tions. However, the purpose of this article 
is to present various simple forms of 
tt combiners ,, which can be quickly con- 
structed for use with medium power 
transmitters > particularly where operation 
on two bands having a harmonic relation- 
ship is involved* 



Legality of Simultaneous Transmission 

It would be nice if one had the 
equipment available to send out something 
like a directional CQ or DX CQ simultan- 
eously on several bands in order to have a 
better chance of making the desired 
contact. However, such operation, unless 
some emergency situation is involved, 
would be considered a waste of spectrum 
space by the FCC and therefore illegal. The 
sending of code practice transmissions 
simultaneously by stations such as W1AW 
is considered legal because of the large 
numbers of amateurs served thereby. 



V 



o 



^r^~o 



< 



i 



v 



> 



O— T5 1 



O 



i 



Fig, 1. Representation of the Functions of a 
combiner unit (dotted tines) when either trans- 
mitting frequency alone is considered. 



JANUARY 1972 



61 



Various emergency and other communi- 
cations that fall under Section 97.91 (b) 
and (d) of the Commission's Rules can be 
carried out using simultaneous multiband 
transmission. There is no hard and fast list 
of situations that one can specifically cite 
where such transmission is allowed, How- 
ever, there are certainly many emergency 
communications situations and situations 
that serve the general amateur radio service 
where the technical advantages of simul- 
taneous transmission is justified to the 
extent that it will be allowed by the FCC 
No special license or permission is required 
for such operation as long as the basic 
operator's license is valid for operation on 
each frequency band used* 

Combiner Operation 

Fig. 1 illustrates the basic functions 
which a combiner network must perform. 
The antenna is assumed to be resonant at 
frequencies Fl and F2 (either broadband 
resonance or a trap-type antenna resonant 
at two different frequencies). When fre- 
quency Fl is considered as the output of 
one transmitter, the combiner network 
must act so the transmission line from the 
antenna is directly connected to the 
transmitter, but the transmission line to the 



other transmitter appears disconnected. 
When frequency F2 is considered, the 
transmission line from the Fl frequency 
transmitter must appear disconnected from 
the antenna. 

There are a number of practical circuits 
that can be devised to implement the 
functions illustrated in Fig. 1. Fig. 2 shows 
two simple basic approaches — a tuned 
circuit (A) and a transmission line stub 
switching arrangement (BK In Fig. 2A, Fl 
is assumed to be lower in frequency than 
F2, The frequencies in this case must not 
necessarily be harmonically related, CI and 
LI are chosen so series resonance is 
produced at Fl, thus connecting the Fl 
transmitter directly to the antenna, CIA 
and LI form a parallel resonant circuit at 
F2, so the F2 frequency cannot flow back 
into the Fl transmitter. On the other 
"side" of the combiner. C2 and L2 are 
series resonant at F2, thus directly connect- 
ing the F2 transmitter to the antenna. 
Since F2 is higher than Fl, the L2, C2 
circuit will provide a capacitive reactance at 
Fl. This capacitive reactance is utilized 
together with coil L2A to form a parallel 
resonant circuit at Fl. Thus, the Fl 
frequency cannot be coupled into the F2 



ci 



',> 



ANTENNA 



U 



L2 



31 



C2 

-4 



CIA 



L2A 



OIF, 



F,<F 2 
(AJ 



ANTENNA 
I 



-* t/4 * ON F, »- ■• 



1/4 * ON 



F 2 — H 



I 



1/2 ^ ON F 2 



I 



< F i 



1/4 4 ON F, 



i 



SHORTED 
END STUB 



OPEN 
END STUB 



F = l/2 F- 



Fig. 2. Basic combiner forms discussed in text. Tuned circuit type (A) and stub type (B). 



62 



73 MAGAZINE 



ANTENNA 



40 M 




45 



8.5 pH 



(A) 



ANTENNA 

4 



ANY LENGTH 




II ff 



40 M 



ANY LENGTH 



ANY LENGTH 



22 ft 



22 ft 



RG-8, 58, 59 t etc 



20 M 



22 ft 



(B) 



Fig. 3, Practical values for 40/20 meter combiner units. Similar combiners may be constructed for 
other combinations of amateur bands. 



transmitter. The practical construction of 
such a network requires only the calcula- 
tion of the component values using stan- 
dard resonant circuit formulas or can even 
be done using a LC reactance chart. As 
high a Q as possible in the tuned circuits is 
desirable both to reduce losses and to 
provide maximum coupling isolation be- 
tween transmitters. 

The simple transmission line combiner 
shown in Fig. 3(B) requires that frequency 
F be one half of that of F2. Normal 
transmission line (coaxial or balanced type) 
can be used for the entire construction. 
The operation can be visualized by first 
noting that both Fl and F2 transmitters 
are directly connected to the antenna. 
However, they are not interconnected to 
each other. On the F2 "side" of the 
combiner, the open end stub is l A\ long at 
FL Thus at Fl, it reflects a short where it 
is connected to the transmission line, the 
length of line between this point and the 
antenna is also chosen to be Y*\ long at Fl. 
Thus, the short is further reflected at Fl to 



be an open circuit at the point where the 
F2 transmitter line meets the antenna. 
Consequently, Fl cannot couple to the F2 
transmitter line. The open end stub on the 
F2 "side" does not interfere with the F2 
frequency because at F2 it is l /z\ long and 
reflects an open circuit across the transmis- 
sion line, At F2 ? the transmission line 
doesn't "know" the stub is there, 

A very similar situation exists on the Fl 
"side" of the combiner. The shorted end 
stub being ViX long at F2 reflects a short at 
the point where it joins the transmission 
line. From this point to the antenna, the 
line is chosen to be l AX long at F2.Thus, 
the short is further reflected to be an open 
circuit at the antenna terminals for F2. F2 
energy cannot enter the Fl transmission 

line. The shorted end stub is ^X long at 
Fl ? and thus reflects an open circuit across 
the transmission line at FL The combiner 
can be readily constructed from standard 
transmission line stock by taking into 
account the velocity factor of the line used 



JANUARY 1972 



63 




TELEVISION INTERFERENCE 

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both a tuned 
combiner which 
ami 40 meter 



to determine the correct physical line 
lengths, 

Practical Examples 

Fig. 3 shows two practical examples of 

circuit and stub type 
can be used to couple 20 
transmitters to a single 
antenna for simultaneous transmission. The 
tuned circuit combiner of Fig. 3 (A) is 
shown as it might be used in a coaxial 
cable transmission line system of any 
impedance- The transmission line from each 
transmitter must, of course, correctly 
match the antenna line impedance. The 
combiner serves only as a coupling and 
isolation network, but not as an impedance 
matching device. The coils should have as 
high a Q as possible. For low power 
transmitters up to a few hundred watts, 
standard B & W or Air Dux coil stock can 
be used; but for higher powers, coils made 
from copper tubing should be used. The 
coils should also be isolated from each 
other by mounting them at right angles to 
each other or using shields between them. 
With each connector dummy loaded by a 
small resistor corresponding to the imped- 
ance of the transmission line used, a 
grid-dip meter coupled to the 3 juH coil on 
the 20 meter "side 7 * of the combiner, the 45 
pF capacitor on that "side" is adjusted for 
circuit resonance on 20 meters. With the 
grid-dip meter loosely coupled to the 8.5 fiH 
coil, that coil is trimmed for resonance on 
40 meters. On the 40 meter "side" of the 
combiner, the grid-dip meter is loosely cou- 
pled to the 3 jiH coil. The 120 pF capacitor 
is adjusted for resonance at the 40 meter 
operating frequency. The 45 pF capacitor is 
adjusted for resonance on 20 meters. 

The stub type combiner of Fig. 3 (B) 
usually needs no adjustment if the stub 
lengths are carefully cut to length. The 
physical lengths shown, for instance, are 
based upon a velocity factor for the 
transmission line of .66, and would be 
correct for such cables as RG-8, RG-58 
RG-59, etc. Standard coaxial cable "hard- 
ware" such as shown in the photograph can 
be used to make all the necessary cable 
interconnections or the cables can be 
carefully spliced together. 



64 



73 MAGAZINE 







" 



•. ■•;■ 



Standard "UHF" type coaxial hardware may be 
used to make ail the necessary interconnections 
for a stub-type combiner. Shown are PL259 plugs 
used with a M-358T adapter and a PL2S8 female 
adapter in the middle teg. 

The schemes shown can be expanded for 
more than dual-band operation, but extra 
tuned circuits and stubs would be necessary, 
resulting in rather complicated networks* If 
you did want to pursue this approach, it 
probably would be better to combine two 
transmitters operating on the lower fre- 
quency bands and two transmitters opera- 
ting on the higher frequency bands in the 
manner shown. Then the outputs could be 
combined using a high and low pass filter 
circuit between transmitter groups for iso- 
lation. 

No combiner network provides abso- 
lutely complete isolation between trans- 
mitters. When tuning up the transmitters, 
each transmitter should be tuned separately 
for proper loading with the other transmit- 
ter inactive. When both transmitters are 
tried, the slight interaction produced may 
require some transmitter retiming, but the 
amount necessary should be minor. 

Summary 

Used properly and legally for the right 
purposes, simultaneous multiband transmis- 
sion can be very useful to better coordinate 
emergency nets operating on different 
bands, placing emergency traffic, etc. The 
proper use of the combiner circuits shown 
will permit the more useful utilization of 
the station equipment available which often 
greatly exceeds the antenna facilities which 
are available, 

. . . W2EEY 



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JANUARY 1972 



65 



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Vernon Fitzpatrick WASOIK 
McLam Park, M-203 
Hancock MI 49930 





PRE-NOVICE 



The pre-Novice "transmitter'' with key. 



TRANSMITTER 



For most aspiring hams code practice is 
the most difficult part of getting the 
ticket. Copying practice can be quite diver- 
sified* There are the records or tapes for 
learning the characters, then the practice 
can be supplemented by listening to Wl AW 
or Novices. Sending is generally limited to 
keying an audio code practice oscillator. 

The following idea is not original or 
unique as the Signal Corps was using it as 
part of its radio operator training in 1948, 
when I took the course. As a diversion, and 
to add interest to our code practice, they 
had a receiver for two students and a 
Meissner signal shifter (a variable frequency 
oscillator) a few feet away. We would close 
the key and locate the signal on the 
receiver; then send to each other We were 
transmitting less than 10 ft but it was our 
first time "on the air." It was quite a thrill. 

Here is a simple building project and 
you will have a transmitter of across-the- 
room capability. The oscillator is an Inter- 



national Crystal Co. OX-LO kit*. Assemble 
the kit following the instructions for 
3000—6000 kHz, as this will permit using 
80 meter crystals. The oscillator can be 
mounted on a piece of wood, but a more 
professional job can be done by mounting 
it on a minibox. The OX circuit board has 
a crystal socket for HC-6/U crystals mount- 
ed on it, I mounted a Cinch-Jones 2 KM 
crystal socket on the minibox, then con- 
nected it in parallel with the circuit board 
crystal socket, This arrangement permits 
using either HC-6/U or FT-243 crystals. AH 
my CW transmitters have a standard 14 in, 
phone jack for the key, so I mounted this 
type of jack on the front of the minibox. 
Whatever type jack you use be sure it is the 
open-circuit type as there is no power 
switch on the oscillator. The key turns it 
on and off- The battery is made by 
connecting four size N-cells in series, then 
taping them in a square. Be sure to tape the 
top and bottom so the battery can't be 



JANUARY 1972 



67 



H 



shorted. Connect a 3 in. red wire to the 
positive terminal and a 5 in. black wire to 
the negative terminal. If you use a larger 
minibox, a plastic or metal holder for four 
penlite cells can be used. 

Final Assembly 

Make all holes in the minibox before 
mounting the oscillator. Mount the oscil- 
lator board. The mounting screws supplied 
with the kit are quite long, 4-40 x % screws 
will be neater. Mount the 2KM crystal 
socket. Mount the key jack. Clamp the 
battery in place. Using two pieces of wire 
5/8 in., wire the 2KM crystal socket in 
parallel with the crystal socket on the 
oscillator board. Solder the red battery 
lead to the 6V terminal on the copper foil 
side of the printed circuit board. Solder the 
black battery lead to the insulated terminal 
on the key jack. The negative circuit is 
completed through the key and jack to the 
minibox, then to the copper foil on the PC 
board. If you use a painted minibox, be 
sure to scrape the paint away around the 
four PC board mounting holes so there will 
be a good electrical contact from the 
copper foil to the minibox. This completes 
the wiring of the "transmitter." Any 80 
meter crystal can be used, but it is best to 
use a Novice band crystal as this will help 
you get used to this band on your receiver. 
Do not connect any type of antenna to the 
oscillator as it is capable of transmitting a 
signal several miles with an antenna. 

If your key is not wired, two-conductor 
speaker wire is good, as it is light and 
flexible and one wire is marked. Connect 
the marked wire (it may have a tracer 
stripe on the insulation or one wire may be 
tinned and the other copper) to the key 
frame terminal. Connect the other wire to 
the insulated key terminal. Connect the 
marked wire to the phone jack outside or 
barrel terminal. Connect the unmarked 
wire to the phone jack tip terminal. If your 
key has a shorting bar be sure it is open. 

Now is a good time to adjust the key. 
Adjust the pivot bearings so the key points 
are aligned; the bearings should be adjusted 
so there is no play or bind. Adjust the 
point gap so a piece of postal card will just 
pass through. The tension adjustment is for 



a, 



CRYSTAL 
SOCKET 



r < 

. — - 
-T- 




JACK 



"I 



L- WHITE DOT COIL 



s^r. 



100 

pF .001 



IH> 



o 



RF 



OX-LO *** j 



Fig. 1. OX-LQ kit has all parts shown inside 
dotted line. OX-LQ kit ($2.95) available from 
International Crystal Manufacturing Co., Inc, 10 
North Lee, Oklahoma City OK 73102. 



the individual fist. It should not be weak 
enough so your hand relaxed on the key 
will close it. Lightly grip the edge of the 
key knob with the thumb and large finger. 
Rest the index finger on the knob. Raise 
and lower your wrist to send. You cannot 
send with your fingers, as they will tire in a 
few minutes. 

Connect 3—4 ft of wire to your receiver 
antenna terminal and turn it on. When the 
receiver is warmed up, close the transmitter 
key and tune the signal on your receiver. 
You are now ready for some real code 
practice. The short antenna on your re- 
ceiver may give you some background 
QRM, This is good, as you will have it 
when you are operating as a Novice, 

If you are practicing with a friend and 
each of you has a transmitter, use crystals 
of the same frequency so you don't have to 
keep retiming the receiver. If you have 
only one transmitter, connect the keys in 
parallel. Connect a two-conductor wire 
from the two terminals on one key to the 
two terminals on the other key. 

I think you will enjoy this method of 
code practice. It is as real as you can get 
without a license. You will find the little 
transmitter convenient for additional prac- 
tice after you get your license, too. You 
may want to add the International Crystal 
PAX-1 transistor rf power amplifier mo- 
dule and have a QRP transmitter for 
on-the-air use, 

. . .WA8GIK" 



68 



73 MAGAZINE 




Wait Schwarz K3WNX 
1 95 Travis Drive 
Pittsburgh PA 15236 



The Problem of Inversions 



The designation of any SSB signal as 
either "upper" or "lower" is simply 
an indication of the position it holds, 
frequency-wise, with respect to its refer- 
ence frequency, which is that which the 
carrier would occupy if it weren't suppres- 
sed. This position, due to the nature of 
sidebands themselves, determines the char- 
acteristics which an individual sideband 
will possess. 

The term "inversion," however, denotes 
a change of the sideband signal from its 
original to the opposite position, which 
change necessarily results in the signal's 
acquiring opposite characteristics as well. 
Accordingly, where no such change in the 
sideband signal has taken place, the signal, 
whether it be upper or lower sideband, 
cannot properly be considered as repre- 
senting an inversion. 

To get along, then, into this problem of 
inversions, let's go directly to the area 
where this problem arises: the mixer stage 
of our SSB rig. While the intended function 
of this stage is simply to convert the 
frequency of either the USB or LSB signal 
generated in an earlier stage to a desired 
output frequency, this stage sometimes 
does a bit more! The "more" bit is the 
alteration or change of position and charac- 
teristics of the SSB signal — an LSB signal 
becomes USB, or a USB signal becomes 
LSB. 

Since an inversion occurs in some cases, 
and in others it doesn't, the question 
naturally arises as to whether the occur- 
rence or nonoccurrence in a given situation 
can be predicted reliably. It can. 

Let's suppose that we're introducing to 



the mixer a 9 MHz USB signal and injec- 
tion frequencies from the output of a 5,0 
to 5,5 MHz vfo, from which mixture we 
obviously obtain output in the 20m band 
by utilizing the sum frequencies, and out- 
put in the 80/75-meter band by utilizing 
the difference frequencies. On either of 
these two bands, our output will be USB, 
the same as our input sideband signal, as no 
inversion will result when any sum fre- 
quency is utilized, and no inversion will 
result in this situation when any difference 
frequency is utilized. If, in this example, 
we used an LSB input signal instead, our 
output on either band would be LSB for 
the same reasons. 

Before presenting an example of a situa- 
tion in which an inversion will occur, 
however, it should be pointed out, even 
though it's pretty apparent that to obtain 
outputs in bands other than 20 and 80m, 
we will require injection frequencies addi- 
tional to those supplied by the vfo alone, 
Premixed injection frequencies for this 
purpose can be obtained simply by em- 
ploying an auxiliary oscillator along with 
our vfo. 

Now, let's suppose we're interested in 
working, say, the 15m band using the same 
9 MHz USB signal. Using a premixed range 
of injection frequencies from 12.0 to 12,5 
MHz, we could obtain outputs from 21.0 
to 2L5 MHz by using the sum frequencies, 
and our output would be USB, the same as 
our input sideband signal, since no inver- 
sion would take place. However, using a 
premixed range of injection frequencies 
from 30.0 to 30.5 MHz instead, outputs in 
the same range (21.0 to 21,5 MHz) could 



JANUARY 1972 



69 



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be obtained by using the difference fre- 
quencies, but here an inversion would take 
place and our output would be LSB. To 
obtain a USB output, using the 30.0 to 
30.5 MHz injection frequencies, our 9 MHz 
input signal would have to be LSB. 

We've offered two examples here in- 
volving utilization of difference fre- 
quencies, in one of which examples we've 
claimed that an inversion will take place, 
and in the other we've claimed that it 
won 7. Since both examples involved differ- 
ence frequencies, there must obviously be 



some difference in their differences. The 
difference in the difference frequencies, to 
keep things simple, could be labeled as 
positive and negative differences, with the 
appropriate label being established simply 
by subtracting the injection frequency 
from the input sideband signal frequency, 
but never the other way around! 

In any case where the injection fre- 
quency is lower than the input sideband 
signal frequency (as when, to obtain 80m 
output, we mixed the output of a 5.0 MHz 
vfo with a 9 MHz sideband signal), a 





Table (.Sideband Inversion Logic 




GIVEN 


Frequency A (USB) 


Frequency B (LSB) 




Frequency G (Inj Freq) 


A or B 


APPLICATION 


Frequency A (USB) 


Frequency B (LSB) 




minus Freq C 


minus F req C 




Mixer Output 1 (USB) 


Mixer Output 2 (LSB) 


GIVEN 


Frequency D (Jnj Freq) 


A or B 


APPLICATION 


Frequency A (USB) 


Frequency B (LSB) 




minus Freq D 


minus Freq D 





Mixer Output 3 (LSB) 


Mixer Output 4 (USB) 



70 



73 MAGAZINE 



positive difference will result. Subtracting 
5,0 from 9.0 gives a positive difference of 
4.0. Likewise, in any case where the 
injection frequency is higher than the input 
sideband signal frequency, as was the case 
when, to obtain 1 5m output, we mixed 
frequencies from 30.0 to 30.5 MHz with 
our 9 MHz sideband signal, a negative 
difference will result. Subtracting 30.0 
from 9,0 gives us — 21, since we're sub- 
tracting larger figures from a smaller one, 
which differences are clearly negative dif- 
ferences. 

Proof covering the claims made in this 
article as to when an inversion will occur 
and when it won't is available in two 
forms, either of which should suffice to 
dispel any doubts concerning the reliability 
of these claims. One involves the examina- 
tion of an actual rig utilizing frequencies 
identical to those used in our examples, 
and the other involves recourse to "side- 
band inversion" logic. 

The popular combination of a 9 MHz 
sideband signal and a 5 MHz vfo, which 
was used in our examples, along with an 
auxiliary oscillator, when needed, is uti- 
lized in the Hallicrafters HT-46 transmitter, 
which makes it one of a number which 
could serve to illustrate the occurrence or 
nonoccurrence of inversions in the manner 
claimed. On the band selector of the 
HT-46, we find the 80 and 20m bands 
marked in red y and all other bands marked 
in white. Encountering this situation cold, 
it would be natural to suppose that some- 
thing happens on 80 and 20 that doesn't 
happen on any of the other bands. But, 
having already read the information of- 
fered earlier in this article, you will have 
guessed correctly that exactly the opposite 
is the case here. The red markings indicate 
the bands on which inversions do not 
occur, and the white markings indicate 
those bands on which they do, even though 
no mention of inversions^ as such, is made 
anywhere in the operating manual on this 
rig. Output in the 20 and 80m bands is 
obtained by utilizing sum frequencies for 
20, and positive differences for 80, in both 
of which situations we claimed that no 
inversion will result, which claim is support- 



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ed by both of these bands being marked in 
red. Output in all of the other bands (40, 
15, and 10) is obtained by utilizing nega- 
tive differences, in which situations we 
claimed inversions will always occur, which 
claim is supported by the white markings 
for each band obtained in that manner. 

Our alternative proof is in sideband 
inversion logic, as offered in Table I. If 
frequency A represents the upper sideband 
of any pair of sidebands and frequency B 
the lower, then, by the definition of 
sidebands themselves, A must be higher 
than B. Frequency C in our chart repre- 
sents any injection frequency lower than A 
or B, and frequency D represents any 
injection frequency higher than A or B. 
The substitution of any actual frequencies 
for the letters in the table will establish 
that, without exception, inversions will 
occur only with negative differences, 

. . .K3WNX 






JANUARY 1972 



71 




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John H. Smith VK3IQ 
83 Bindi Street 
Glenroy, Victoria 
3046 
Australia 



A MEDIUM FREQUENCY CONVERTER 
FOR HIGH FREQUENCY RECEIVERS 



When today's "oldtimers* were 
learning the code in the '20s and 
30s, they copied a lot of it on the 
"medium-frequency shipping band." To- 
day's communication receivers seldom cov- 
er the broadcast band, let alone frequencies 
below 530 kHz, There are many interesting 
signals to be heard on 500 kHz; passenger 
liners, cargo ships, coastal stations, com- 
mercial traffic, ship position reports and 
weather bulletins. The MCW signals on 
these frequencies pack a distinctive punch; 
fellow ex-marine radio operators will know 
what I mean; and recently I decided to 
settle an urge to hear them again. Almost 
every ham I know has one or more old BC 
radio sets in his junkbox, and this seldom- 
used junk is just what you will need for 
this simple medium-frequency converter. 
Component values are not critical, and the 
unit gives excellent results. 

My station receiver is a Drake 2B and 
tunes from 3.5 MHz to 4.1 MHz on its 
lowest frequency band. With this conver- 
ter, I can tune from 400 kHz to 1000 kHz, 
using the 2B on 80m. I used a 3100 kHz 
crystal with a trimmer capacitor across the 
socket to adjust the crystal frequency to 
exactly 3100 kHz, and get accurate fre- 
quency readout from the 2B dial. Any 
similar crystal will do if you make suitable 
allowances; e.g., 3200 kHz will give a 
tuning range of 300 to 900 kHz, If you 
have a 3500 kHz crystal and are not 
interested in the lower part of the broad- 
cast band, you can use that instead. In 
theory, this will give you a tuning range to 
600 kHz. I tried a 3500 kHz crystal, and 
found that I could hear signals as low as 
200 kHz, despite the fact that the conver- 
ter input will only peak to just below 400 
kHz with the component values given. 
From 200 to 400 kHz you will hear a 



variety of radio navigation beacons, and 
from 400 kHz upwards, you will tune the 
shipping band. 

The tuning capacitor is an old two- 
section variable with both sections in paral- 
lel, and a 100 pF mica added to give a total 
capacity of about 1000 pF, If your junk- 
box offers you a three-gang type, by all 
means use it The coil is a standard 
broadcast band antenna coil, from a set 
that used a wire antenna rather than a loop 
or ferrite rod* If in doubt as to which 
winding is which on the coil, the common- 
ly used connections are shown on the 
circuits of Figs. 1 and 2, If you have an 
unmarked coil, you have an excellent 
chance of wiring it right first time if you 
measure the dc resistance of the windings 
with an ohmmeter; the tuned winding 
normally has the lower resistance of the 
two. As well as the coil and capacitor, the 
old radio that I stripped had a triode 
hexode converter tube (6K8), Having used 



TO h# 
PtCVH 

I 



j& 



tOO TO IOOO pF 



ANT. 





RFC 



900 IOO 
F pF IpF 

rh rh 



6K8 

2 7 

6.3 VAC 



*250V 



Fig. J, A medium-frequency converter for high 
frequency receivers using a 6K8. 



JANUARY 1972 



73 



the coil and capacitor, I used the tube, too. 
Pentagrid tubes such as the 6SA7 and 
6BE6 are not suitable for this circuit due 
to their internal construction; however, an 
excellent modern tube for this converter is 
the 6U8 triode pentode. Circuits for both 
tube types are given. 

Use as low a voltage as possible on the 
oscillator section plate, consistent with 
reliable starting of the crystal. This mini- 
mizes spurious mixing and breakthrough of 
unwanted signals. If your B+ supply differs 
greatly from my 250V, it may be necessary 
to alter the values of the B+ line resistors, 
but they should be near enough for volt- 
ages from 220 to 280V. If you use a 6U8, 
you may have to experiment with the 
oscillator plate resistor to find just what 
value is best; I suggest you use a 500 k£2 
pot at first, and adjust it to a setting that 
gives good results; then replace it with a 
fixed resistor of the same value. The bypass 
and coupling capacitors in both circuits are 
not critical in value; in Australia, a very 
convenient source of ,005 (jiF disk ceramic 
capacitors is discarded starter units for 
fluorescent lights. Each starter contains a 
glass-enclosed switch and a bypass capaci- 
tor. The rf chokes can be any that you 
have on hand; if one is better than the 
other, use the best one in the mixer plate. 



TO hf RCVR 

I 



JT 



o 



100 TO IOOO pF 



i/2 sue 




6U6 



4 5 

6.3 VAC 



+ 250V 



Fig. 2. Converter circuit built with 6U8. 



The cable from the converter to the re- 
ceiver antenna input should be coax of 
course; anything in the 50—750 range is 
ideal. 

The power requirements could probably 
be met from most receivers, but I take my 
power from the lightly loaded supply that 
feeds my vfo. The converter was built on a 
small chassis of 9 by 3 by 2 in., which suits 
the space I had available on the radio desk. 

In use, I select the required frequency 
on the Drake dial, peak the preselector 
tuning, and then peak the required med- 
ium-frequency signal with the converter 
tuning capacitor. My station antenna is 
only a 67 ft long, Windom-fed, inverted 
vee, 25 ft high at the center, but seems 
adequate for 500 kHz reception, as I have 
heard signals over 2000 miles away at 
night, and up to 500 miles by day. 

The coastal radio stations call on 500 
kHz, and use one working frequency, 
generally between 414 and 492 kHz, 
though one or two frequencies have been 
allocated between 514 and 520 kHz; the 
power is around 2 kW. Ships call on 500 
kHz and have 410, 425, 448, 454, 468, 
480, and 512 kHz for working frequencies. 
Most cargo ships run 500— 900W, and 
passenger ships run up to 2 kW. All stations 
observe two "silent" periods each hour; 
two 3-minute periods beginning at 1 5 past 
and 45 minutes past the hour. 

Hams who are boating enthusiasts will 
find the local coast stations' weather bul- 
letins of interest, and with code speeds 
varying from 15 wpm to over 25 wpnu 
there is plenty of practice available. The 
quality of code varies, too; from the 
roughest imaginable, to the perfection of 
machine type Morse. 

This converter can be used with any 
receiver that covers 3.5—4.1 MHz or high- 
er; build it yourself and see how interesting 
the lower frequencies can be. 

My grateful thanks are due Gil Moody 
(VK3ZR) for suggesting that the mixer 
plate load be an rf choke. Without this 
advice, I would certainly have used tuned 
output, and run into no end of trouble 
with tracking problems and receiver over- 
load. 

. . /VK31Q" 



74 



73 MAGAZINE 



F. G. Rayer G30GR 

Longdon Heath 
Upton on Severn 
Worcester, England 



EASY 

END FEED 



MATCH 




If we look for the quickest, easiest, 
cheapest way to put out a signal on any 
band from 80 to 10, we see that the 
answer is an end-fed wire. This has 
extremely variable characteristics in terms 
of radiation, depending on length, band, 
direction, etc. On any particular band it is 
generally about as good as a dipole, if 
similar in length to a dipole for that band. 
On lower frequencies it may be a quarter 
wavelength or less, while on higher 
frequencies it would be two half-waves, or 
more. 

The beauty of the end-fed wire is that in 
practice it can beany length. This means it 
is strung between the two best available 
supports, with one end (adequately 
insulated) descending into the shack, it 
may be vertical, sloping, horizontal, or a 
mixture of these, and is probably longer 
than about 20 ft, though it is unlikely to 
be over about 125-150 ft unless you are 
lucky with space. 

Its feed impedance will be a variable 
thing, according to frequency, length, and 
other factors. The usual transmitter or 
transceiver pi output tank is mostly 



intended to work into a load of about 50 

to 7512. So inevitably, this and the end-fed 
wire will be incompatible on some bands. 

Z Match 

An impedance or Z-matching device 
between transmitter and end-fed wire 
corrects matters so that all but extremely 
short wires will load the transmitter. Figure 
I is a simple but practical circuit. L is a 
robust tapped coil, and the variable 
capacitor is about 150 pF, wide spaced for 
other than low power. This was found 
satisfactory for any wire from 10 to 1 50 ft. 
With shorter wires arcing occurred. The 
longer wires naturally radiate better. 



ANY LENGTH 



v 



XMTR CO 




COAX 




EARTH 









Fig. 1 . Circuit of the type used. 



JANUARY 1972 



75 




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Fig. 2, Coil and other details. 

This is a good opportunity to use a 
surplus inductor, The one actually used 
was wound for the job, however. It had 26 
turns of 1 6-gage wire on a 2Vi in. diameter 
ceramic form, the winding taking up 3 l A in. 
Stout leads soldered on go to the tabs of a 
12-way rotary switch (Fig. 2). The switch 
selects the following numbers of turns — 
(coil shorted), 1, 2, 3, 5, 7, 9, 12, 16, 21, 
and 26 (whole coil). 

An swr indicator may be put in the coax 
from the transmitter to Z match. A good 
earth ground is helpful. Remember , there 
may be considerable rf on the antenna 
connection. 

The receiver or transceiver S-meter 
should give a guide to tuning. Begin with 
the capacitor at minimum, and no turns in 
circuit. Rotate the switch to bring up 
signals. When the best point is passed (too 
many turns) rotate the switch back one 
position, and peak the variable capacitor 
for best reception. 

Adjustments are somewhat similar for 
transmitting. If the TX pi output capacitor 
is at about a setting which would work into 
around 50-7557, rotating the capacitor 
with the correct number of turns in circuit 
will show a point where the system draws 
power and can load the transmitter. 

It was found that with quite long wires, 
the variable needs little or no adjustment 
over a fair section of a band. But with 
short wires, it has to be retuned with other 
than small changes in frequency. 

. . .G30GR" 



76 



73 MAGAZINE 



Charles Gelsinger 

4000 Carnino Del Valle SW 

Albuquerque NM 87105 







for 2 Meters RE VISITED 



When I saw the coat hanger antenna 
for 2 meters in the June 1969 73, 
I knew it was just what I was looking for, 
so I made one. It works nicely, but a few 
changes can make it even better. Since 1 
use one 10 ft length of coax to connect 
transmitter to dummy load and transmitter 
to SWR ? I wanted to use the same piece of 
coax on the antenna, but the original 
article had it soldered to the antenna 
directly, I made two modifications on this 
antenna, and now the coax is removable 
and it is now impossible to put an eye out 
with it. The grounding plane section of the 
antenna is dismantled and put together as 
follows: 

1. Put two connectors, No, SO-234 
hack to back and solder them to- 
gether with about Vi in. space be- 
tween them (see diagram). 

2. Cut a piece of plexiglas 3/8 in. thick, 
the size of the connectors (about 1 x 
1), and cut out the area indicated on 
the drawing, then put it back to- 
gether. Now you can screw the cable 
on and off when packing the antenna 
or storing it. 

If you are afraid someone might get 
poked in the eye with the grounding 
section of the antenna, put four foam balls 
on the ends of the elements and paint them 
a bright color. 1 painted mine a bright 




COAX 

TO 
XMTR 



3/8 in. X I in. X ! m 
PLEXIGLAS, HOLE 
PATTERN AND 
CUT-OUT TO FIT 
BOTTOM OF 
50-239 FITTINGS. 



Fig. 1. Construction details of the improved 

groundplane. 



orange and it really stands out. If you like 
your homebrew equipment to have your 
call letters, paint them in black on the 
colored balls. It really stands out, Good 
luck. 

. . -Gelsinger" 



JANUARY 1972 



77 



"MODEL A" 



Here's what the amateur operator has 

been looking for. 

*****»-» AtiA-mm nAkin It's new, all new! It's a State-of-the-Art, all 

2-METER AMATEUR BAND ... ' . ■ u- l j j 

solid state 2-meter nam rig which we designed, 

VHF-rM we built, we tested and we priced the Simpson 

way. Low. 

PUT THIS BABY IN YOUR CAR! THE EASY WAY! 

Time was when you had to modify to go mobile. 

Not with the model A! It's as mobile as its name. 

Enjoy 2-meter mobile along with the thousands of 

others who are enjoying this fast-growing part of 



rf*i , < \ 









nun 



r 



n 



% 






mi 



PRICES & SPECS SUBJECT TO CHANGE WITHOUT NOTICE 



• COMPLETE WITH MICROPHONE, 
MOUNTING BRACKET, CRYSTALS 

• CHANNEL 1 - 146*34-146.94 

• CHANNEL 2 - 146.940 46.94 

AMATEUR NET PRICE 

*249 

fob Miami 

(INCLUDES 2 PAIR CRYSTALS) 

Over-size front mounted speaker 
Press-to-talk microphone with coil cord 
8 T /2 in, wide x 216 in, high x 1 1 in, deep 
G-10 glass epoxy boards. 



TUNING FREQUENCY RANGE: 144-148 Mhz. 

FREQUENCY STABILITY; 0.001% 

(from -30 : to —60 C) 

NUMBER OF CHANNELS; 4 Independent 

selector switch 

USABLE SENSITIVITY: 0.5 uv or less for 12 db SIN AD 

SPURIOUS RESPONSES ATTENUATION: 

Greater than —60 db* 

AUDIO OUTPUT: 2,0 wotts with less than 10% 

distortion. 



POWER OUTPUT: 



6 watts into 50 ohm 



IM 

2295 N.W. 14th St 



LECTROIMICS, INC. 

Miami, Fla. 33125 • Ph: 633-3261 




Uses 

the Simpson 
Model A 



Tlhis is an amateur model of the very 
well known Simpson Model T marine 

transceiver, a four channel 150 MHz FM 
transceiver The amateur who is looking for 
an American built unit of exceptional quali- 
ty would do well to take a close look at the 
Model A, 

Some of the features which make this 
transceiver so interesting to the FMer are its 
uncompromising construction, with nothing 
left out for economy. There are four trans- 
mit channels and four receive channels, and 
any may be paired with any other if you live 
in a mixed-up repeater area with machines 
on, say, 22-76, 22-82, 16-76, 25-76, 25-88, 
28-88, 31-88, etc. Independent switching of 
the receive and transmit channels just may 



• * 




7TC\\ 



FM 




be the way things are heading. 

By tilting the oval loudspeaker back and 
building in a small air coupling section in 
front of the speaker, the Model A is capable 
of putting out a remarkably good sound. If 
your car has much more noise than a Rolls 
you may just need all the loudspeaker you 
can get to hear what is coming out of your 
receiver and you may find the usual 2 in, 
speaker a whisper in a windstorm when you 
rev up through the gears* 

Separate boards are used for the receiver 
and transmitter functions, a fact which has 
alerted some of the more devious technicians 
in our midst to the possibilities of using the 
Model A for a repeater. All it takes are a few 



JANUARY 1972 



79 



wiring changes and a carrier operated relay 
to make the basic change. To my knowledge 
there are well over a dozen active repeaters 
around the country today using the Model A 
boards. 

The transmitter puts out a minimum of 6 
watts and uses the popular 6 MHz crystals 
(the same as the Regency transceivers). That 
power level is quite adequate for most 
repeater operation and represents a good 
compromise for your car battery longevity. 
You can always put in an external booster 
amplifier for boondocks work. 

The receiver has a ceramic filter with 6 
dB skirts at 13 kHz and 60 dB at 36 kHz, 
which means that a strong signal on 9 1 will 
not wipe out both 88 and 94 for you as it 
will in some other popular receivers. One 
good strong 9 1 machine can raise Ned for a 
hundred miles on three channels unless 
everyone has good selecting receivers. Sure, 
you can always buy a $1 5 filter and put it in 
yourself, but that means drilling holes and 
work which could be avoided if you chose a 
receiver with narrower bandwidth. 

The oscillators all use diodes for switch- 
ing, which means that you can actually 



switch channels from any distance you wish. 
This system is ideal for use with remote base 
installations where you might have the trans- 
ceiver up on the top of a mountain and 
remotely operated by 450 MHz link or 
phone wires. You may not be able to live on 
top of a mountain or a tall building, but you 
might be able to stick a remote rig up there, 
which is the next best thing. 

The oscillators are padded enough so you 
can buy inexpensive low tolerance crystals 
and zero them in. The pads are right out 
there where you can tune them too, rather 
than requiring a deformed midget with a lot 
of patience to get your crystals on channel. 

The Model A is in a flat pack that wiU fit 
under the dash of most cars and still leave 
plenty of leg room. The box is made of 
extruded aluminum side rails with vinyl 
covered aluminum top and bottom covers 
and a front panel of injection-molded Cyco- 
lac. The circuit boards are glass expoxy and 
the parts are machine-wave soldered to 
them. In all, it is an extremely professional 
and commercial quality job of construction. 

It also works. 

...W2NSD/I 



TS -155C SIG. GENERATOR, ireq. range 
2700-3400 MC — units in good condition. Sold for 

115V 50 1G00 cy. 1 phase P/S included in 
generator. Shpt. Wt, 35 lbs. 

TS-323/UR FREQ. METER, portable crystal con- 
trolled heterodyne-type instrument Excellent cond 
Shpt. Wt. 35 lbs. Price $49.95 

WTNTROnTx MODEL 850 INDUCED WAV€ 
FORM ANALYSER, This unit, in conjunction with 
your present oscilloscope, permits you to view wave 
forms in the range from audio thru MHz without any 
direct connection. The probe is simply placed over 
the tube in question and the wave form is displayed 
on the oscilloscope. It may also be used as a high 
gain amplifier to increase 'scope sensitivity- Excel 
lent for T. v\, radio, amplifier, end transmitter repair 
and maintenance. Brand new, with probe. 
Shpt. Wt. 13 lbs. Price: $19.95 ea. 

TRANSFORMERS 115/230 V input 60 cys. 300 V, 

10 ma. 12.6 VCT @ ,5A 

Shpt. Wt. 2 lbs. Price; $1.00 ea. or 6 for $5.00 

TRANSFORMER SP 327 1000 1000 "oT 

12OO-0 120O @200 ma. 110 or 220 VAC 

Shpt. Wt. 15 lbs. Price. S9.95 ea. 



TRANSFORMERS F610 STANCOR 6.3 CT 10A 


Shpt. 


Wt, 


5 lbs. 




Price: $235 ea. 


F21A TRIAD 6 3 CT 


20A 




Shpt, 


Wt 


6 lbs. 




Price: $335 



DIODES 1 amp. bullet type diodes with silver leads 
600 piv @ 1 amp . , . . 10 for $1.00 or 110 for $10.00 

METERS PANEL TYPE WESTON MODEL 123S 
0-500 micro amps full scale calibrated .005 to 500 
roentgens/hours, 270 degree scale, approx, 3" dia. 
excellent for wavemeter etc. New and in original 
boxes £1*95 ea. or 3 for $5.00 

3" RD. METERS 
0-5 amp. A.C. WESTON MODEL 304 
0-1,5 amp, A,C T WESTON MODEL 476 
0-300 amp. D.C, 50 M.V. FS WO/shunt 
Price: $2.50 or . , . ,3 for $6.00 












2 1/2 RD. 
0-30 amp. A,C. Triplet Model 231 
0-35 VDC Phaostrom Model 200 
0—1 MA DC meter relay Weston 1093 
Price: $1 ,95 or 



.3 for $5.00 



0-100 amp. Weston 1533 W/ext* shunt 

ll#TS * ......r.ii*.... .<..*..*..■ 



* * * » 



* * iffiliv J 



#360 TEKTRONIX WAVE FORM INDICATOR 

bandwidth DC to 500 KC. Sensitivity .05/DIV. 

5QWD1V. waveforms required tor hor. deflection. 

§jize: 4" x 12" x 14" 

#160A regulated power supply for above indicator. 

Size: 4"x 12" x 14" 

^62 wave form generator for above indicator. Size; 

4" x 12" x 6" 

SPECIAL PRICE FOR ALL 3 UNITS 
Shpt, wt. 35 lbs. Price: $99.95 



400-550 MC RECEIVER Xtal controlled, 4 section 
trough line — Front and w/crystal mixer. 5 stage 
l,F., 28V. input, D.C, to D.C. toroid inverter P/S. 
Stitamintature tubes — 1-5636, 1-6896 t 2-6111, 
3-5718, 4-6205. 4 miniature Babcock relays, and 
toroid bandpass filter. Heavy alum, watertight case. 
6" m 8 J1 x 10' . 18 lbs $14.95 



334" 


Rd 


D.C. 


Ammeter 30 0-30 . 


* * # ■ 


$2.50 


2 V 


Rd 


DX 


. Ammeter 


300 W/Shunt 


and 


Leeds 


Weston 201 


... 


■ ■ - • • 




$6.95 



R 11 A LOW FREQ. RECEIVER 190-550 KC 
modern Q 5'er Shpt. Wt. 8 lbs. $7.95 or 2 for S 14.00 
^R 4S Ft EC, freq. 230-250 mc. 

5|ipi. wt. 45 lbs- Price: $24.95 

^rT282 D/GR trans, freq. 225-400 mc. 

$hp\. wt. 150 lb*. Price: $3930 

rfcv 431 A trans, freq, 230-250 mc, 

Shpt. wt. 7 lbs. Price: $18.95 



CAPACITORS 



65,000 MFD 5V 
30.000 MFD 10V 
25 P 000MFD 25V 
20,000 MFD 30V 



Computer Type 
20,000 MFD 25 V 
35,000 MFD 15V 
40,000 MFD 10V 



Price: 3/$1 .00 or .... » .,...*.... 10/S3.Q0 



1206 S, NAPA ST., PHILADELPHIA, PA. 19146 • PHONE: 215 HO 8 7891 • 215 HO-8-4645 



All prices are F.O.B. our warehouse, Philadelphia, Pa. All merchandise described accurately to the best of our know/edge. Your pur- 
chax* money refunded if not satisfied. Terms are cash. Minimum order is SS.QO. Ail merchandise subject to prior safe. J 



80 



73 MAGAZINE 




feature 



feature 

after 

feature 



In addition to those pictured—there's 
500 watts P.E.P. power input—digital 
readout to 100 Hertz---husky match- 
ing 115VAC power supply/speaker 
unit and external VFO as an available 
accessory. 

Add all of these and you have the bril- 
liant SB-36— a beautiful experience in 
operating convenience and enjoyment 

See it at your dealer— write for data sheet. 




SSB/CW TRANSCEIVER 








Separate 
bandpass 
filters for 
USB and iSB. 
Absolutely 
no carrier 
shift when 
changing 
sidebands! 



LINEAR 
SYSTEMS, INC* 

220 

Airport 8lvd. 
Watsonville, CA 
95076 








i-i 



AMATEUR RADIO 

NOVICE-CLASS UCEH 

STUDY GUIDE 




AMATEUR RADIO 

GENERAL 

CLASS 

LICENSE 

STUDY 

GUIDE 




AMATEUR 

RADIO 

ADVANCED 

CLASS 

LICENSE 

STUDY 

GUIDE 



n 



AMATEUR 
RADIO 

EXTRA ^ 

CLASS ^ 

LICENSE] 
STUDY I 
GUIDE j 






A The Novice Class Li- 
cense Study Guide has not 
yet been published in 73 or 
in any other magazine. 
This book contains all the 
basic technical information 
need to pass the Novice 
License with flying col- 
ors. . .and is invaluable as a 
basic text for understand- 
ing the General Class Study 
Guide. Profusely illustrated 
and so clearly written that 
just reading it is enough to 
permit most applicants to 
pass their exam. $3.95 
value. 



B The 73 General Class 
Study Guide has helped 
thousands to easily pass 
their General License the 
first time through. At $9 a 
whack, isn't it foolish not 
to hedge your bet with this 
comprehensive and simple 
book? No other study 
guide is as complete or as 
easy to read. None. A 
$4.95 value. 



C The Advanced Class 
Study Guide has proven to 
be the only complete text 
for preparing to pass the 
Advanced Class license 
exam. Never before has 
radio theory been made so 
simple. After just reading 
this book it is almost im- 
possible to fail that exam. 
And remember that in ad- 
dition to the trouble of 
going to the FCC to take 
that exam r there is a little 
matter of $9 you have to 
ante up. Why take a chance 
on failing? $5.95 value. 



D The Extra Class License 
Study Guide makes all that 
complicated electronic the- 
ory seem simple. A little 
study with this book and 
you will be ready to face 
the FCC examiner with 
'Confidence. A $4.95 value! 




JV! BULLETIIM 





E The 7 3 DX 
handbook has every 
DX aid you could 
hope for, , .QSL 
Bureaus, postage 
rates worldwide, 
DXCC and WTW 
country lists and re- 
cord pages, maps of 
many areas of the 
world with prefixes, 
plus a complete 
wal l-sized world 
map with each 
book! It is profusely 
illustrated with pic- 
tures of many of the 
top DXers, plus art- 
icles on working DX 
on the different 
bands. There are 
great circle bearing 
maps and charts, 
and more. . .more 
. - .more. 



F The FM Anth- 
ology has reprints of 
all the articles and 
technical data from 
the early issues of 
the FM Journal, No 
FM library is com- 
plete without this 
data, much of it just 
not available else- 
where, $5.95 value, 

G The BEST of 
FM is a compilation 
of the best articles 
that appeared in the 
FM Journal from 
March 1968 through 
June 1969, the last 
of the magazine. 
Read the extremely 
controversial Chron- 
icles of 76. Plus do- 
zens of technical 
and circuit articles 
available nowhere 
else. $4.95 value. 

H Transistor Pro- 
jects for the 
Amateur is cram- 
med with over 40 
interesting construe* 
tion projects cover- 
ing receivers, con- 
verters and transmit- 
ters, many in the 
VHF region. If you 
like to build you 
will blow your mind 
over this book. 



ft? 



73 MAGAZINE 






GET ONE BOOK FREE WITH EACH DIFFERENT SUBSCRIPTION. 
GET THREE BOOKS FREE WITH EACH LIFE SUBSCRIPTION. 

Accept ONE BOOK FREE with our compliments for each different $6 subscription you enter. Free 
Gift Books can be sent to each subscriber or to the donor. One gift book per $6 subscription, wherever 
they go. All subscriptions will be entered to start with February 1972 unless otherwise noted. On 
renewals or extensions of subscriptions please include the address label from the magazine wrapper or 
renewal notice. This offer good in North America only. Foreign readers may participate by adding one 
extra dollar per one year subscription. 

Offer expires Feb, 19, 1972 
Please enter subscriptions for the following, starting with the February 1972 issue. 



That's right, all you have to do is buy 
a one year $6 subscription to 73 and you 
are eligible for a free book (postpaid) of 
your choice or a set of back issues (FOB 
73 HQ). You say you want two books? 
Fine, no trouble whatever, just buy a 
little old gift subscription for a friend or 
DX buddy and ask us to send you the 
book or back issue package. 

Can you buy two years for $12 and 
get two books? No, sorry about that, but 
the whole purpose of this unusual offer is 
to Increase the circulation of 73, not to 
just give away a few thousand books free 
of charge. We know that once an active 
amateur starts reading 73 he has a hard 
time ever being without it again and so, 
though we pay dearly for that first 
subscription, we eventually make it up 
come renewal time. And keep in mind 
that the more subscribers we have for 73 
the better magazine we can give you. 

Over 3000 great articles have appeared 
in our back issues and most of them are 
just as good today as the day they were 
printed. You will have the time of your 
fife reading all those wonderful issues you 
missed, We have separated the back issues 
into three packages, issues from 
1960-1964 (I), 1965-1967 (II), and 
1968-1970 (III). These back issue 
bundles are put together by illiterate 
apple pickers borrowed from other ham 
magazine staffs and thus there is no 
possibility of our guaranteeing any parti- 
cular issue in your bundles . . • you take 
pot luck. Due to the $12 value that we 
are making available in these back issue 
packages (12 different back issues in each 
package), we must ask that you foot the 
shipping charges. Please include $1 to 
cover handling and mailing of these great 
big packages of back issues. 

If you prefer that we send a book or 
back issues to your buddy along with his 
subscription, just indicate this on the 
farm. 



73 Magazine, Peterborough NH 03458 
New □ Renewal or Extension □ 



Name- 



Call 



Address - 



City. 



.State, 



ZIP. 



Circle book wanted: A B C D E F G H I II III 

1 year $6 D choose book Life $73D choose any 3 books 



73 Magazine, Peterborough NH 03458 
New □ Renewal or Extension □ 



Name 



Call 



Address, 



City- 



State- 



ZIP, 



Circle book wanted: ABCDEFGHIIIIII 

1 year $6 D choose book Life $73 D choose any 3 books 



I- 



73 Magazine, Peterborough NH 03458 
New □ Renewal or Extension □ 



Name 



.Call. 



Address 



City 



State 



ZIP. 



Circle book wanted: ABCDEFGHIIIIII 

1 year $6 □ choose 1 book Life $73 □ choose any 3 books 



73 Magazine, Peterborough NH 03458 

New □ Renewal or Extension □ 



Name, 



.Call 



Address. 
I City 



State. 



.ZIP- 



Circle book wanted: ABCDEFGHIIIIII 

1 year $6 G choose 1 book Life $73 G choose any 3 books 



IAMI IARY 1Q79 



ft -3 



RADIO BOOKSHOP BIG DEALS 



VHF ANTENNAS This hand- 
book is a complete collection 
of up-to-date information 
about VHF and UHF anten- 
nas, with design hints, con- 
struction and theory. If youV 
been wondering what array 
you need, this book will give 
you enough background to 
make the right decision. 




BUY BINDERS FOR YOUR 

73 and win the love of a 
beautif 1 1 girl. Gorgeous red 
binders look great on your 
shelves and also keep the mag- 
azines from disappearing or 
breaking. Come with set of 
year stickers. Get enough bin- 
ders to protect all those back 
issues too. 
1205 %S 




GUNSMOKE? Blow your 
mind on our back issue bar- 
gain bunch, 30 (count 'em) 
assorted (we hope) back is- 
sues, all before 1968, for the 
incredibly low price of $6 
postpaid (hardly pays for the 
postage). These are packed by 
slave labor (to cut costs) so 

E lease ignore notes calling for 
elp, etc., that may be slipped 
into the bundles. 



1204 



• $6 



TIRED OF CRUMMY LOG BOOKS? 

Try a pad of W2NSD log sheets. 
Why use a I 93 1 log book in 1 97 1 ? Do 
we guarantee that this is the best log 
ever devised by the mind of man? You 
bet we don't! It is a good one and 
you'll find it a tremendous improve- 
ment over anything you've ever seen 
before. 
1210 ppd USA $2 



Mail book orders to: 

RADIO BOOKSHOP 

Peterborough NH 03458 



Send Repeater Bulletin forms to: 
73 Inc., Peterborough NH 03458 




FM ANTHOLOGY Vol. 1. 
This book is largely a col- 
lection from FM Bulletin, edit- 
ed by K 67 MV H and 
WA8UTB. The material is ta- 
ken from the editions of Feb- 
ruary 1967 through February 
1968, 
1009 . . , $5 

FM REPEATER HANDBOOK 

K6MVH, Book is required for 
all repeater operators and 
must reading for all FM'ers. 
Only complete book on the 
subject. It is also one of the 
best selling books in amateur 
radio today. 
1010 Hardbound $6:95 

"THE BEST OF FM" A huge 
selection of FM Journal's fin- 
est technical and conversion 
articles, never before reprinted 
in any other magazine. The 
concluding segments of those 
co ntroversial "CHRON- 
ICLES"! Selected FM editor- 
ials to show a broad view of 
the problems faced by FM'ers, 
This book comprises Volume 
II of the FM anthology, and 
includes an "Editor's Choice" 
selection of topflight articles 
from FM Journal Fiom March 
1968 to May 1969. 

/ 1} I 1 t , , . , | . i a * * ■ m w w V ^T . \7 KS 

EDITORS & ENGINEERS 
RADIO HANDBOOK Hard- 
bound. W6SAI (17th edition) 
reduced for clearance, limited 
supply available for fast acting 
amateurs. Last chance to get 
this great book before it is 
gone forever. 
10 1 9 



DX CHART 

You will use this DX chart eve 
day that you are on the air. That** 
guarantee. This is the fastest way 
find the angle to swing that bea: 
These charts are made by a eompui 
and are custom made for your lo< 
tion. The angle and distance to all 
the countries of the world are on tl 
chart. This chart should cost you Sf 
but it doesn't . . . send only S4 a 
thank your lucky stars that there is 
ham who is offering this service mt 
for fun than profit. 

You Need an ATLAS 

Lucky for you we still have atlas 
These are not cheap junky discou 
house type trash atlases, these are 1 
finest ever made, up to date, profusi 
illustrated, exquisite in appointme 
a joy to behold, a pride to own, a k 
couldn't do better. Hammond spa 
no expense to turn out the very fir 
atlases in the entire world. The o 
expense that is spared is the one 
spare you by making these extrao 
nary books available. Where else 
you buy a S20 atlas for only 
Order now. we have a limited sup 
and can't get more before Chris tn 



, . m $ I u 



DX HANDBOOK Inciud 
giant world country-zone w< 
map. Articles on QSL desif 
secrets, winning DX contest 
DXCC rules, DXpeditions, r 
ciprocal licensing and mar 
more. World postage rate 
WAZ record lists, time charl 
propagation, etc. Special ha 
maps and bearing charts, 
must for the DXer. 1021 . 



i 



NEW REPEATER BULLETIN 

-Repeater users in New England and Eastern New York (including Loi 
Island) may be interested in a subscription to a Repeater Bulletin whi< 
is available free to qualified amateurs in that area. This bulletin w 
attempt to provide communications between the 40 or so repeater grou 
now using 2m FM in the Northeast. The Bulletin will provide not on 
news of activities, plans and items of interest on each of the 40+ repeat* 
but will also attempt to keep up with the news of new equipment, ne 
circuits, and provide a forum for discussing repeater problems. We ho; 
to reprint some of the more interesting FM articles from past issues 
73, plus excerpts from past, present and future FM books. It should 
provocative and interesting. 

To qualify for a free subscription you must live in the area described ai 
be accepted by the publisher. Please fill out the qualifying form below 
furnish the required data on a separate sheet of paper. 



Name 



Request for Free Subscription to the Repeater Bulletin 
Call . . 



Address,. 
City 



State 



ZIP 



-Year first licensed 



Class of License 

Include list of equipment being used, base, mobile, hand; make, mod 
power. Repeaters being used (indicate if closed), call, location, f re que 
cies in and out, tone burst. Other bands and modes used: Amatei 
outside the New England/Eastern New York area may subscribe to t 
Repeater Bulletin at the rate of $3 for 12 issues. Subscriptions will 
accepted at the discretion of the publisher and may be rejected wit ho 
explanation. 



84 



73 MAGAZir 





Reviews 



The CT POWER Amplifiers 




One of the neatest, most professional wiring jobs 
we've ever seen! 



Knock that repeater right off the mountain/ 



This new concern in Hawthorne, Cali- 
fornia, is producing a line of eight two 
meter power amplifiers which are being 
marketed by Henry Radio as part of their 
Tempo line. The 45 and 60 watt output 
amplifiers are available for driving powers of 
one, five or ten watts, while the 100 watt 
output models can be driven with five or ten 
watts. 

While the ten watt output of most of the 
FM transceivers is quite adequate in the 
primary coverage area of repeaters, what 
amateur has not fretted when he was far 
enough out to copy the repeater solid, but 
could not trigger it? A hundred watt ampli- 
fier will give you quite a few more miles of 
good solid repeater usage> you may be sure. 

But fellows, be fair, put in a switch to cut 
out the amplifier when you are close enough 
in so it isn't needed. No one is going to love 
you if your signal comes crashing in on top 
of all the other mobiles. Use these power 
amplifiers as a force for good, not as a means 
for getting on every shoot list within re- 
peater range. 



IANUARY 1972 



85 



^™ 



■— 



GATEWAY 

ELECTRONICS 

6150 DELMAR BLVD., ST. LOUIS, MO 63112 

314-726 6116 

MOTOROLA 432 Mhz TRANSCEIVERS - Model 
T44-6A - Complete with all cables, control 
head, and mic. - ship wt. 75 lb. $25.00 

RCA 150 Mh? TRANSCEIVERS - Model CMC-30 
CAR FONE — Complete with all cables, control 
head, and mic. - ship wt. 75 lb. ..... S85.00 

12 VOLT A RELAY - ship wt Vi lb. ..... . $3,50 

2C39 A (Ceramic version) — ship wt. Y* lb. . . $6.00 
6397{final used in P 33 etc ) -ship wt.1/8 lb, $4.50 

1AD4 - ship wt. 1/8 lb $2,50 

5678 - ship wt. 1/8 lb. $1.50 

MOTOROLA 6 VOLT XTAL OVEN - 

ship wt. Vi lb $1 .00 

RCA 12 VOLT XTAL OVEN-ship wt. 54 lb, $3,50 
GE 12 VOLT XTAL OVEN-ship wt. % lb. $3.50 

4 COND. MIC. CABLE -Coil Cord - 2 shield- 
ed — 2 unshielded - 30" retracted — 15' ex- 
tended - ship wt. 2 lb $6.50 

BRUSH 4 CHANNEL CHART RECORDER - 
Model RD2341 with DC Amplifiers and cables- 
ship wt. 75 lb. $250.00 



See other ads for our IC prices and write for our 
catalog, Stop in and see us when you 're in St. 

Louis, 



JEFF-TRONICS 



SOLA CONSTANT VOLTAGE TRANSFORM^ 
ER, type CV, ^22-962 5E93. 1000 Va, 
1 08- 1 32 volts input, 1 1 8 volts out, 8.48 amps, 
60 Hz, Brand new. Shpg. Wt. 65 lbs. 
S35.00 each * 3 for $95.00 



POWERSTAT, 230 v. input, 0-230 v. out, 35 
amps max., 60 Hz. 14" wide, 614" high. No 
cover or dial. Used, exc. Wt. 75 lbs. 
$22.50 each ... ,5 for $100.00 

(above 2 items ship by REA or motor freight) 

Panoramic SB-8B T-1 000 Spectrum Analyzer 5 

Mc. IF. With power supply . $200.00 

APR-4Y receiver with CV-253 plug-in. Tunes 

38-1000 MHZ. 115v. 60 H? $200.00 

HP 100 D Frequency Standard $135.00 

HP 524-B Counter, 10 Mc . $250.00 

526-A Video Amplifier plug-in for 524-B, C, D . 

£Rf) on 

526-D Phase Unit plug-in for 524-B, C, D 
Measures phase angle to 0.1 degree . . $100.00 
HP 715-A Klystron Power Supply .... S60.00 



Send for catalog of surplus electronic equip- 
ment & parts, 25tf for handling* 

JEFF-TRONICS 

4252 Pearl Rd., Cleveland, OH 44109 



One hundred watts from your mobile rig 
will stomp everything in town, including 
most of the home rigs. At 13 amperes it will 
deflate your battery unless your car is set up 
for this type of demand. An alternator 
system has a lot to recommend it when you 
urc asking this from the car. Perhaps the 45 
watt unit is more practical for your system 
with lis 5A demand. 45 watts is still a lot of 
soup and should easily double your range 
into the repeaters. 

Are these amplifiers difficult to install? 
No. Being small, 3 M x 4" x 8 ! r for the 100 
watt model, they will mount just about 
anywhere. My own preference is on the 
firewall under the front hood where the 
battery cable can be relatively short and 
deliver the 13.8 volts in good shape to the 
unit. A coax cable from the amplifier runs 
through the wall to the back of the trans- 
ceiver, while the antenna connects to the 
other end of the amplifier. 

When you turn on your transmitter a bit 
of the rf is rectified as it enters the amplifier 
and this actuates a send-receive relay, switch- 
ing the antenna to the output of the 
amplifier. A 2N2222 transistor is used for 
the switching function, and TRW PT-8710s 
are used for the amplifier, with one as a 
driver and three in parallel in the final. As 
soon as the ten watts of rf stops coming 
tli rough the hose from the transceiver the 
relay reconnects the antenna to the trans- 
ceiver, cutting the amplifier out of the 
circuit. 

If you are having trouble getting into a 
repeater you might consider going the power 
amplifier route. 

In Action! 

Using the Tempo 100 watt amplifier I 
have yet to find one repeater that 1 can hear 
well that I can't get into. With the amplifier 
off, my signals are frequently either marginal 
or else just don't make it at all when I get on 
the other side of a mountain, even though I 
can hear the repeater enough to copy it. 

If you can get into every repeater you can 
hear, then you have nothing to gain from 
adding an amplifier. If your signals fade out 
before the repeater, perhaps this is your 
answer as it was mine. 

. . .W2NSD/1 



86 



73 MAGAZINE 



John J. Schultz W2EEY 
1829 Cornelia St. 
Brooklyn NY 11227 



OPTIMAL VERTICAL 
ANTENNA LOADING TECHNIQUES 

The author discusses the various techniques used to had vertical antennas. 
From the viewpoint of reasonable performance, ease of construction and 
bandswitching, a combination of top and base loading is favored. The 
construction of a pratical antenna is illustrated. 



Many amateurs are faced with antenna 
placement situations which do not 
allow the erection of full-sized antennas. A 
loaded type of vertical antenna is often the 
only antenna possibility. Often, even a trap- 
type vertical cannot be used on the lower 
frequency bands because of the size of such 
an antenna and its support requirements. 
The only choice then is to use as long a 
vertical antenna as possible with as much 
loading inductance as necessary to resonate 
the antenna on a desired band. The physical 
length of such an antenna may be 1 /6 or less 
of the electrical length it represents through 
inductive loading. 

The subject of how to produce efficient, 
extremely short-loaded antennas has been 
the subject of numerous studies by com- 
mercial and military organizations. The pur- 
pose of this discussion is not to delve into 
the more advanced techniques which have 
been developed since such techniques often 
require special construction and special 
equipment for a relatively small gain in 
antenna efficiency. This approach may be 
necessary in some situations where the capa- 
city of the power supply for a portable 
transmitter is limited and the only possi- 
bility to improve the radiated signal is 
through increased antenna efficiency. In the 
amateur case, and particularly for the new- 



comer who starts with a low-power trans- 
mitter, it is often easier and more economi- 
cal to first try increasing the transmitter 
output level (via an inexpensive linear ampli- 
fier, for instance) rather than getting in- 
volved with complicated antenna construc- 
tion projects. Therefore we will discuss only 
the simple forms of antenna loading which 
have been well proved and which are easy to 
build. The material is particularly oriented 
toward the newcomer who would like to 
construct a simple loaded type of vertical 
antenna that will give reasonable results on 
one or more high-frequency bands. 

Loading Variations 

A full-length quarter-wave antenna will 
have the current distribution shown in Fig. 
1A. If the physical length of the antenna is 
made shorter than the required electrical 
length, a loading inductor can be used to 
establish the correct electrical length. When 
this is done, the current distribution may 
appear different than in Fig. I A, depending 
upon where the loading inductor is placed* If 
the loading inductor could be distributed 
over the entire length available for the 
antenna (helical loading) the current distri- 
bution would look the same (Fig. IB), 
Placing the loading inductor either at the 
extreme top or bottom of the antenna will 



JANUARY 1972 



87 



POWER SUPPLIES 

Excellent for 12 volt transceivers, general 
purpose experimenting, or for LC. logic. Each 
supply features LC. voltage regulation. Output 
voltage varies less than 1% of supply voltage 
from no load to full load. The power supplies 
are also current protected. A momentary short 
will not harm this unit, 

30,00 

30.00 
30,00 
35,00 
40.00 

TERMS: Send check or money order plus 1.00 
postage. Allow 3 weeks for delivery, 

RIM SYSTEMS 

1879 Princeton Dr, Clearwater FL 33515 



P51 


5 volts 


@1A 


P91 


9 volts 


@1A 


P121 


12 volts 


@1A 


P122 


1 2 vo I ts 


@>2A 


P125 


12 volts 


@>5A 



SPACE-AGE TV CAMERA KITS & PLANS 



]& 



BE A PIONEER IN HOME TELECASTING' Bui 14 m own 
TV CAMERA. Model XT-H Strict D, %\ 16.9$ pp. 5d<d- 
Sfot*. $f^by**t«f construction manual. High quality* 
Gannett id any TV without jnadrii cation* Idta* |« hams, 
experiiwnttn, akcalian, industry , ate, 

PHONE or WRITE for CATALOG, 

DIAL *02-ftfl7-3771 



Many attiir kid, parti and plans available Including starter 
kiti, focus /M. coils, vidican tvbei r can it, plani, etc 

tsoi n. broaoway ATV Research Dakota city, neir. 68731 



FM Schematic Digest 

A COLLECTION OF 

MOTOROLA SCHEMATICS 
Alignment, Crystal, and Technical Notes 

covering 1947-1960 
136 pages IWx 17" ppd$6.50 

S. Wolf 

11 00 Tremont Street 

Boston, Massachusetts 021 20 



fiEH CORNEL 



TUBES! 



I 



tube 



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CORNELL'S 
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THE VIBROPLEX 

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833 Broadway, 
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WORLD QSL BUREAU 

5200 Panama Ave., Richmond CA USA 94804 

THE ONLY QSL BUREAU to handle all of 
your QSLs to anywhere; next door, the next 
state, the next county, the whole world, Just 
bundle them up (please arrange alphabetically) 
and send them to us with payment of 5£ each. 



/ 



/ 



/ 



/ 



/ 



/ 

/ 
/ v 



/ 



/ 



i 



% 



(A) 



IB) 



/ 



°3, 



U 



(C) 



(0) 



Fig. L The dotted lines show the current distri- 
bution on a full length l AXvertical antenna (A) and 
various forms of physically shorter, inductively 

loaded antennas. 



produce the current distributions shown in 
Figs. 1C and ID. Various points can be 
advanced for either top or bottom loading. 
Top loading has the advantage that the 
greatest current flow will take place in the 
metal rod section of the antenna and, 
therefore, less I R losses will take place in 
i he loading inductor on top. Bottom loading 
has the advantage that the loading inductor 
can easily be band switched, Also, if the 
loading inductor is constructed of heavy 
enough wire, the losses can be held to a 
tolerable level. 

Aside from placing the loading induc- 
tance either at the extreme top or bottom of 
the antenna, one could also place the loading 
inductance at the center of the antenna 01 

place a portion of the inductance at the top 
and a portion at the bottom of the antenna, 
The current generation of mobile antennas 
generally uses center loading because of a 



oo 



73 MAGAZINE 



/ 



1 



/ 
/ 



/ 
I 



/ 



1, 



Fig, Z Splitting the inductive loading to both ends 
of the antenna produces the current distribution 

shown. 



combination of electrical and mechanical 
factors* The loading inductor need not be as 
heavy as a base-loading inductor to keep 
losses to a reasonable level, and the physical 
placement of the inductor allows a flexible 
upper section for the antenna, as well as 
access to the inductor for bandswitching by 
changing inductors. However, for home- 
station usage, the proper placement of part 
of the loading inductance at the top and 
bottom of the antenna, as shown in Fig. 2 ? 
has a better combination of electrical and 
mechanical advantages. The placement of 
part of the loading inductance at the base 
does not optimize the situation where the 
highest current flow is through the metal rod 
of the antenna, but it is also true in a 
practical situation that the most severe 
ground losses would still take place at the 
base of the antenna. So the actual increased 
loss that results as compared to solely top 
loading the antenna is a small price to pay 
for the convenience factors involved in 
bandswitching and impedance matching the 
antenna to a transmission line. The top 
loading that is used insures that a good 
portion of the highest current flow will take 
place in the metal rod. 

Finally, the splitting of the loading induc- 
tance between the base and the top of the 
intfenna greatly simplifies construction of 
the antenna for home station usage where a 
single long aluminum or steel piece of tubing 
s used as the main element of the antenna. 



CRYSTALS FOR FM RIGS 

Regency, Varrtronics, Drake, Tempo, Swan, Stan- 
dard, etc. Receive $4.50 Transmit $5-50, Also 
crystals for police receivers — Regency, Bearcat, 
etc. $4.50 

Quick Delivery — Postpaid (3rd Class) 

DERRICK ELECTRONICS, INC. 

P.O. Box 457B, Broken Arrow, Okla. 74012 







r//&/7& CX-7A 

New "A" model Mow Available 
Still $2195 - Great New Reliability 




Phone/write Don Payne, K4ID 

For a brochure or big trade-in on your gear 

PAYNE RADIO 

Box 525 Springfield, Tennessee 
days (615)384-5573 •nights (615)384-5643 



You can have the 



lOPmsiGNAL 



with our base station antenna. The AT-2FM offers 
you 6 dB Gain, 1.5:1 V,S,W,R, (or better) and 3 
Mega-Hertz Bandwidth centered around 146.94 
Mega-Hertz. 

For full details write: g^ 357 r,r. 5 

AN-TEK INDUSTRIES Elkhart, Indiana 46514 



LEARN (MPfO 




Album contains three 12 
LPVZ'yihr, Instruction, 



** 



THE EASY WAY! 

• No Books To Read 

• No Visual Gimmicks To 
Distract You 

• Just Listen And Learn 

Based on modern psychological 
techniques— This course will take 
you beyond 13 w.p.m* in 
LESS THAN HALF THE TIME! 
Available on magnetic tape, 
S9.95 - Cassette, $10.95 



EpSILON PS] RECORDS 



508 East Washington St., Areola, Illinois 61910 



VHF CONVERTERS 

We manufacture a complete line of converters for 
50 through 432 MHz. Models to suit all needs. DX, 
FM, ATV, MARS, etc. A postcard will bring our 
new FREE CATALOG with pictures, schematics, 
specifications and prices, 
l A mci P.O. Box 112 

JMIVC u Succasunna, ISL J. 07876 

LABORATORIES TEL: 201 584-6521 



4SMbblh£ 25 $24Q95* 



• 6 separately switchable transmit & 
receive channels. ■ 2 meter transceiver 



'Suggested list price 



""PEARCE-SIIVIPSOIM 

DIVISION Of £U4bbir\£ CORPORATION 

PO Box 600 Biscayne Annex Miami, Florida 33152 



IANUARY 1972 



89 



KITS 



Sub-Audible tone 
Decoder $9.95 




Encoder $8.95 



Compaiibte with all sub -audible tone systems such as 
Private Line, Channel Guard, Quiet Channel, etc. 

Glass epoxy PCB's& silicon xstrs throughout 

Any reeds, except special dual coil types may be used 
Motorola, G.E., RCA, SDL,, Bramco, etc 

Alt are powered by 12 vdc 

Use on any tone frequency 67 Hz to 250 Hz 

Small si^e 1.5 * 4 x IS" 

All parts included except reed and reed socket 

Postpaid - Calif, residents add 5% sales tax 

COMMUNICATIONS SPECIALISTS 

P.O. Box 153 Brea CA 92621 




i 



cap bfi tes 
Tube test data 



Power 
>arts. 



TV 7/U ELECTRON TUBE TESTER 

POR" DYNAMIC MUTUAL CONDUCTANCE TYPE 

^ Used to test <md measure the per 
^k formante capabiiif >es, and to defer 

-T| i me the rejection limits for Elec 

-H 1 C iron Tubes used in Receivers, to 

L 1 St power Transmitters, & in many 

other electronic equipment. The 
tests made are for dynamic mutual 
conductance, emission, shorts, gas. 
noise, continuity, pilot tamp, etc 
Test sockets are for loctaL octal, 4 t 
5. 6. 7 pin, Norvat 9, 7 pin mi ma 
e. submin. rd & flat, acorn, etc 
With special adapters (THAT ARE 
OPTIONAL* 829, 832, 2C39 and 
sub mm, tubes with long leaclu also 
reM""ed 1 15 Volt 50 to 1000 cycles 
test leads and pm straighteners for 7 8t 
9 pin are includi i Size G I d x 3 T 2 x 15 3 Y 4'\ Wi. 20 lbs 
PRICES Used, serviceable $19.95 Checked - S25.00 

Auapier for &C39 S500 For B29/S32 $5.00 For 

sub min Lg. Lead S3 .00 All prices FOB Lima. OH 

Deot. 73 - SEND FOR NEWCA TAL0G 



cj|i d wm 
1016 E EUREKA • Bom 1105 * LIMA. OHIO ■ 45B02 



HOT CARREER DIODES: HP2B0I1 5 9Q.1?^S1 0.00 Matched hy HAL 4/$4.?5 

ZENEBS 1N47ZM(3.6¥K tN4733(5,M H lN47354E.2v), 1N4?36(B,M 

1N473Q(fl.M. lN4742(1Zv), 1N4T42(12*J. I watt. ...$ ,7fi 

LINEARIC5: 7Q9N S .75 lOBl/hON,,., S1.Z5 741N S1.&0 

WT^M MC142H*.. 53.75 MC1d%5. S3 25 MC1590G S&.6Q 

" DIGITAL ICS; F^L9Z3......S .90 MC7S7P... S3.30 MC723P «S J5 

MRU MC7MP. ...SUO MCBBQP S350 MCS9B* S2.00 

MC724P MC725P. MC7t&P. MC792P „. ...it. OS 

MC771P, SI, 75 MCS7DP S3 JO MC9760P „.W.4& 

DIP TTl: 74&0. ?40J r 7402. 7410, 7420, 743D, 744Q , _^ „ ....™ S 48 

7404, ?405 ...S 60 7441. 74§6. 749ft S3-M 7442„.„ ...SMS 

747?. ....._ t ,75 7473, 7474 .... SI. 05 7475 S? 40 

7416 „ $1,15 7«D. 7492. 7493 ^„.«J0 74121 , Si 4D 

FETS: 40673MOSFET Si 60 MPf ^ S * »»■ * S5 

TDROiOS Imliiiw Gtiifril CF 102-06. CF10J-O1, HF101 02. ._ - S .50 

CM02Q3 SJ.25 FEBROXCUfiE FEftfllTE BEADS ...1011.25 

CllfCH IC SOCKETS MCS, 14- DIP.... £ JO UMCS, IB-DIP -S _M 

MANY 01 HER DEVICES AMD COMPONENTS IN STOCK. WRITE f OH CATALOG 

HAL DEVICES 

Box 365L, Urbana I L 61801 • 217-359-7373 







FRECK RADIO SUPPLY 

38 Biltmore Ave., Asheville, N.C. 28801 

(704) 254-9551 

Serving the amateurs for 43 years 

Large Stock of Used Equipment. FREE list 
upon request. We stock Collins • Drake • 
Galaxy • Kenwood •Signal One •Swan 
• Tempo •Hy-Gain •Newtronics* Several 
Others. 

BEFORE YOU TRADE - TRY US! 

Bank Americard — Master Charge 

Tenny Freck W4WL - Sandy Jackson Mgr. 

Harvey Nations W4VOV 



APPROX 60 MH-65 TURNS 
NO. 14 AWG, 2-I/2 m DlA. 



lOff ROD, 1-1/2 in DlA 



50-70A LINE 



[ 




SAME AS TOP 
LOADING COIL 



GROUND POINT 

Fig. 3, Dimensions and coil sizes for 80 f 40m 
antenna. 



Practical Example 

Figure 3 shows a simple antenna using a 
10 ft aluminum rod and top and base 
loading which I constructed for use on 80 
and 40m. The maximum amount of top 
loading was utilized that would still permit 
enough base loading to be present on 40m so 
a coaxial transmission line could be tapped 
on the base-loading inductance for a proper 
impedance match. For the 10 ft rod, this 
meant a maximum top-loading inductance of 
about 60 (aH. Since the top loading is fixed ? 
this meant that the base-loading inductance 
has to be increased as necessary on 80m to 
resonate the antenna. Again, about 60 juH is 
necessary. The coil dimensions shown in Fig. 
2 are those for which B&W or Air Dux coil 
stock is available. If possible, it would be 
desirable to increase the diameter-to-length 
ratio of one or both coils (maintaining the 
same inductance) so that the diameter is 
about half the coil length. This would raise 
the Q and improve the overall antenna 
efficiency. Such construction would make it 
more difficult to tap the transmission line on 
the base-loading coil but it should be easy to 
implement for the top-loading coil. The 
top-loading coil used is a salvaged coil from 



90 



73 MAGAZINE 



a commercial trap-type vertical antenna. The 
necessary loading inductances for other 
bands or with other lengths of tubing can 
either be calculated from handbook data or 
it can be easily experimentally determined. 
In the latter case, the maximum amount of 
top-loading inductance is used on the highest 
frequency band that still allows a sufficient 
amount of base-loading to permit matching 
the transmission line. The base loading is 
then increased as necessary to resonate the 
antenna on the lower frequency band. 

An swr meter is the only instrument 
necessary to adjust the antenna. Starting on 
the highest frequency band, the minimum 
amount of inductance is used in the base coil 
that permits the transmission line to be 
tapped on with a 1:1 swr. On the lower 
frequency band, the base coil tap is first 
changed to bring the swr down and then the 
transmission line tap readjusted to finally 
lower the swr. It may be possible to find a 
compromise tap point for the transmission 
so its position does not have to be changed 
ivhen changing bands. The actual changing 
}f the coil or transmission line taps can be 
lone with relays or manually with clips, as 

iesired. 



nummary 

No simple, short-loaded antenna will be 
ixtremely efficient on the lower frequency 
>ands. However, the antenna described will 
vork reasonably well for its size and it is a 
iractical solution for a simple to construct 
nd inexpensive antenna where space is 
imited. One point that should be carefully 
observed in installing the antenna is to 
rovide a good ground connection either in 
tie form of radials or connection to some 
irge metal structure. If no ground connec- 
on possibility exists where it is desired to 
istall the antenna and no room exists for 
idials, two antennas with similar loading 
oil arrangements can be combined to form 

vertical dipole, or they can even be 
lounted at right angles to each other in the 

> rm ° f an L " . . .W2EEY 



ARNOLD'S ENGRAVING 

Personalized 

ELECTRIC " 

ON-THE-AIR 
SIGN 

WITH CALL 



TATIOM 

WA2ZHA 

CH THE AIR 



Works on 
110 VAC 

$12*95 




WA2ZHA 



Mefaltei Lapal lor- $1.50 Metaltex Tie Clip* $2.25 

ARNOLD'S ENGRAVING 

2041 LIndtn St. Ridge wood, N.Y. 11227 



WE PAY HIGHEST CASH PRICE 

for Electron Tubes & Semiconductors 

Immediate Payment on Unused Tubes 

H& L ASSOCIATES 

EJizabethport Industrial Park 

Elizabeth, New Jersey 07206 

(201) 351 4200 



■ ■ 



NU SIGMA ALPHA 

International Amateur Radio Fraternity. Mem- 
berships now available. Includes wall certificate, 
J,D, card, newsletter, and more. Send for free 
brochure. 

BOX 310 
DEPT. 73, BOSTON MA 02101 



HRL 



DEVICES 



HAL ID-1 REPEATER 

IDENTIFIER 




$75 



oo 



Circuit board wired <£ tested* 

TTL logic* Power line frequency counter for 3 minute 
or less timing and control. Easily reprogrammable 
diode ROM uses only 27 diodes (depending on call) to 
send DE "any call". Low impedance audio with 
volume and tone control. All circuitry including PS on 
small G10 glass PC board. Write for full details. HAL 
DEVICES, BOX 365. URBANA, ILLINOIS 61801 



DATA ENGINEERING INTRODUCES 

FREQUENCY MARKER: 7 markers, harmonics to 150 MHz. 
TWIN-LEVEL KEY: Electronic touch, all solid state. 
ADVANCED KEYERS: i —Iambic, dot/dash memory, var. 
weighting, monitor, auto, character and word spacing. 2 — As 
above, plus SOO-bit message memory, reprogrammable at 
normal keying speed. 

FIVE-YEAR WARRANTIES. Send far free catalog. 

DATA ENGINEERING, INC. 
Box 1245, Springfield, Va. 22151 



HW12.22.32 OWNER 

New three band modification kit delivers the 
performance of your transceiver on 5—200 Kc, 
band segments. 80/40/20 Mtr. SSB/CW coverage. 
Perfect for Civil Defense nets. Complete kit price 
only_$69.95 ppd. Complete assembly manual 
"1 ppd. Send 5Q£ for illustrated brochure. 

DYNALAB RADIO CO. 

215-28 Spencer Ave., Queens Village NY 11427 



MMUARY 1972 



91 



FOR THE PROFESSIONAL AMATEUR SONAR (2 ITieterS 



TRANSMITTER 




RECEIVERS 



(from 144 to 
148 MHz) 

COMPLETE FLEXIBILITY FOR 
FOR MOBILE -BASE -HAND HELD 




model FM3601 

> 3 Channels with Jnstant Push Button switching 

> Solid Stated-using the Widest quality silicon transistors 
^ Netting trimmer for each receive and transit crystal 

^ High quality mechanical fitter for adjacent channel refection 
} Military-grade, gtass-epoxy printed circuits 
} Rugged, serviceable design - Compact, but not crowded 
} Quick removal tray mount for security 

> 25 transistors, 1 IC f 1 MosFet, 16 Diodes 

t Receiver R.F, stag© protected from overload 

> Olodo^^r^elttci ©imitate FET thixfer 
^ Dual vari-cap phase modulator 






Complete with microphone, moblte mounting 
tray and 2 pair of crystals, (146 94T/146.94E and I4G.34T/146.94R) 
Model PS-2923 AC Regulation Power Supply . $39.95 



Model 2307 

VHF-FM 
TRANSCEIVER 
5 CHANNELS 
HAND HELD PORTABLE 

• Provides immediate voice con- 
tact with Base Stations, Mobile 
Units and other portable trans- 
ceivers • Compatible with ALL 
2-way communications systems 

• Snap-in Nicad Battery Pack 
cartridge • Receiver and trans- 
mitter can be operated on inde- 
pendent frequencies ■ Electronic 
mode switching /no relays * Re- 
ceiver and transmitter sections 
are individual mo<tules for easy 
servicing • Sensitive adjustable 
squelch 

compatible with 
collapsible antenna 
and shoulder strap. 
Less crystals & battery cartridge* 



Sonar Radio Corporation 73 Wortman Avenue, Brooklyn, N.Y. 11207 



NEW! 

REPEATER 

ATLAS 



Maps showing 
the area covered 
by most of the 
repeaters. 
An up-to-date 
listing of the 
open repeaters 
nationwide. 



II and CJUIUIM 



< II 



; . \ locothhk-" 1 - ;. v " 

flPn^NG FflEQUHP£S v - ? * k <3? 



^ 



This is the book to have for your glove 
compartment in your car. When you are 
travelling now you will know what chan- 
nels to use to get into the repeaters. Say 
you are driving along the New York 
Thru way . . . what repeaters can you use 
and over what range? Check the ATLAS. 

Perhaps you are flying into Chicago for 



a business trip or convention s . . what 
repeaters can you use with the little rig 
you plugged into the rented car? Check 
the ATLAS! 

Or are you Just getting the FM bug and 
wondering whether there is a repeater 
which covers your town? Check the 
ATLAS, 

Going on a vacation and want to route 
yourself through as many repeaters as 
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Is your repeater group thinking of 
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Repeater Atlas Order Blank 

73 Magazine Peterborough NH 03458 



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$1.50 enclosed for one copy of the ATLAS. 
$10.00 enclosed for 10 copies of the ATLAS 

(club special). 



92 



73 MAGAZINE 



PEP 

Distributor Of Electronic 
Components 

MONEY BACK GUARANTEE 




1 AMP 

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2 AMP BULLETS 

12 200V $1.00 

00 V Sl.OO 
800 V Sl.OO 



CIRCUIT BOARD SPECIAL 

A -Approximately 200 diodes— 7 transistors- 
over 50 resistors complete with board!— $1.25 

40 Amp. Stud 24 V 7 for 51. OO 

Plastic low power transistors PHV No Test 25 for Sl.OO 



PRV 



FULL WAVE BRIDGES 

2Amp 3Amp | SAmp f lOArnp 



50V 


1.2 5 




1.35 


1 


1 


.50 


1,70 


lOOV 


1.50 


1 


1,60 




1 


.75 


1.95 


200V 


1,75 


1 


1»&5 


1 


2 


.OO 


2.20 


400V 


1 2.00 


1 


2.10 


1 


2. 


,25 


| 2.45 


600V 


| 2.50 


| 


2*60 


1 


2 


75 


| 2.95 


SOOV 300 

SILICON 

PRV 1 


| 5.10 

CONTROL 

AMP 


! 3.25 3,45 

RECTIFIERS 
3 AMP 7 AMP 


SO 




.20 


l 


.25 




1 


.30 


loo 




25 


1 


.30 






.35 


200 




40 


! 


.45 




i 


.30 


300 




60 


J 


.70 






.80 


4O0 


. 


75 




85 






93 



soo 






I 



too 



GOO j ... | . . I 1.30 

TRIACS 

PRV 1 AMP i 3 AMP 6 AMP 10 AMP 1 15 AMP 



100 



,40 



.50 



.75 



1.00 1 20 



200 



.65 



.75 



1.O0 



1.40 



1.80 



300 1.00 1.10 1.25 



l.&O 2.2 



400 



1.30 



1.40 1.80 2.30 



SOO 1.60 



1.80 



2.10 



2,75 



NO SALES TAX - WE PAY POSTAGE 
OTHER PRODUCTS ON REQUEST 

PARK ELECTRONIC PRODUCTS 

P.O. Box 99, N. Salem, IMJ-I. 03073 

603-893-0276 



BRAND NEW FREQ-SHIFT TTY MONITOR: 
NAVY OCT-3: FM Receiver type, .req. range 1 to 26 MHz 
in 4 bands, cont. tuning. Crystal cahb. Reads up to 1 »O0 H/ 
delation on built-in VTVM. Cost $1100.00 each! In 
original box, with instruct, book k et-rd, fob Mariposa, Cal. 
Shpg wt 1 10 lbs 49.50 



HIGH-SENSITIVITY WIDE-BAND RECEIVER 

COMMUNICATIONS •BUG DETECTION 
• SPECTRUM STUDIES 

381000 MHZ AN/ALR-5; Consists of brand new tuner/ 
converter CV-253/ALH in original factory pack and an exc. 
u rd» checked OK & grtd main receiver R-444 modified for 
120 v. 50/60 h/. The tuner covers the range in 4 bands; 
each band has its own Type N Ant. input. Packed with each 
tuner is the factory inspector's checkout sheet. The one we 
opened showed SENSITIVITY: 1.1 uv <*i :iK_4 mhz. 0..» at 
133 mhz. 5 at 53H mhz, 4 s . at 77K mh/, 7 at 1 ghz. The 
receiver is actually a 30 mhz IF ampJ. with all that follows, 
including a diode meter for relative signal strengths: an 
atten. calibrated in 6 db steps to —7-1 dn, followed by an 
AVC position: Pan.. Video &. AF outpuLs; switch select pass 
of ±200 kh/. or ±2 mhz; and SELECT AM or FM! Wuh 
Handbook & pwr. input plug, all onh 375.00 



30 m Hz Panadapter for the above 



129.50 



REGUL. PWR SPLY FOR COMMAND, LM, ETC. 

PP-J06/U: Metered. Knob-adjustable 90-2 7 O v up to 80 ma 

dc; also select _m AC of 6.3 v 5A t or 12.6 v 2*2 A qt 28 v 
2^i A. With mating output plug & all tech. cata. Shpg, wt 

*»liJ I OS* t + .........a...+ ,+ ..**..4 + -------- - • I _3* .. J _J 

BARGAINS WHICH THE ABOVE WILL POWER: 

LM-C*) F'req, Meter: 125-20 MHz, .01%, CW or AM, with 
serial-matched ealib, book, tech. data, mating plug. Shipping 

W t . it) I US . + *.d,i4..t. T ._.... . . . * . , , . ...... . . ?J / i3v 

TS 323 Fret§. Meter: 20— 480 mhz. 001^ 169.50 

R23A/ARC5Conimand Q-5'er 190—650 KHz.e-tccond 16.95 
A.R.C.R22 Command rt.r 540—1600 KH/ ( exc.cond . 17.95 
A.R.C. R15CMIL K-509)Command, 108-135 MHz.new 27.50 



NEMS CLARKE ^1670 FM Rcvr 55-260 MH/ 

J .1 Fh- %. J. t IT %\ _ _ - _ . ________ fc- *- _P * ^u.^mrr-ttT--^- — •--- 

WWV Rcvr/Comparator 2** - 20 MHz, solid state . 

PSB Converter CV-591 A/URR (455 KHz) w/book 
erris ^2 (*> Field Strength Meter is a red-hot 

from 150 KH/ to 20 MH/, only 

Empire Devices NF-114 RFI meter is a red-hot 

from I 50 KHz to 80 MHz . , v , , .,.**..... 

Spectrum Analyzer Give-Away: Polarad TSA with 
head: 1 0-1 0O0 MH/. Looks good, sold as-ls - 



475.00 
250.00 
137.50 

receiver 
. 95.00 

receiver 
295.00 

SIT 1 

350.00 



We have the best test-equipment & oscilloscope 
inventory in the country so ask for your 
needs . . . don't ash for an overall catalog . . « 
we also buy, so tell us what you have. 



R. E. GOODHEART CO., Inc. 

Box 1220 GC, Beverly Hills, Calif. 90213 
Phones: Area Code 213, Office 272-5707 






WANTED! TRADE-INS 

WE NEED THE FOLLOWING TRADE-INS FOR NEW FACTORY BOXED DRAKE 
AMATEUR GEAR. IF YOU HAVE, WILL ALLOW ON YOUR CLEAN TRADE-INS: 




COLLINS 7SA4 S/N ABOVE 3000 
COLLINS 75A4S/N BELOW 3000 

COLLINS 32V3 

COLLINS R-388/URR OR 51J3 , - 

COLLINS R^389/URR 

CENTRAL ELECTRONICS 100V 
CENTRAL ELECTRONICS 200V 



,.♦_.. $300,00 

$150.00 

$350.00 

. . _. $300.00 

, . „ S350.00 

S400.00 



. 



R4-B 



SWAN 350C WITH 1 17XC $300.00 

SWAN 500C WITH 1 174C $400.00 

HAMMARLUND HO 145C OR X , $150.00 

HAMMARLUND HQ 180A OR C , , , $225.00 

SBE-34 TRANSCEIVER .,..,. $175.00 

MILITARY R 390/URR RECEIVER $450.00 

MILITARY R-390A/URR RECEIVER . $550.00 

MILITARY TS-497B/URR SIGNAL GENERATOR $140-00 

MfLITARY TS-510A OR HP608DSIG GEN $400.00 

MILITARY ARC102 OR 618T TRANSCEIVER ,_,.,,,,,_ $750.00 



TR 6 




TR-4 



TELL US WHAT YOU HAVE AND NEW DRAKE GEAR YOU WANT Write or phone 813-722-1843 
■ SLEP ELECTRONICS COMPANY ■ ■ ■ ■ 2412 Highway 301 Ellenlon FL 33532 ■ 



ANUARY 1972 



93 






Build this nineli 



Schober Recital Organ 

for only 
1850 ! 




^Includes 

finished walnut 
console. (Only 
$1446 if you build 
your own console.) 
Amplifier, speaker 
system, optional 
accessories extra. 

You couldn't touch an organ like this in a store for 
less than $4 t 000-and there never has been an eleo 
tronic instrument with this vast variety of genuine 
pipe-organ voices that you can add to and change 
any time you like! If you've dreamed of the sound 
of a large pipe organ in your own home, if you're 
looking for an organ for your church, you r H be more 
thrilled and happy with a Schober Recital Organ than 
you could possibly imagine — kit or no kit. 

You can learn to play it — and a full-size, full-facil- 
ity instrument is easier to learn on than any cut*down 
"home T ' model. And you can build it, from Schober 
Kits, world famous for ease of assembly without the 
slightest knowledge of electronics or music, for de- 
sign and parts quality from the ground up, and— 
above ail — for the highest praise from musicians 
everywhere. 

Send right now for the full-color Schober catalog, 
containing specifications of all five Schober Organ 
models, beginning at $499.50. No charge, no obliga- 
tion. If you like music, you owe yourself a Schober 
Organ! 



The y^cilO&e/l Organ Corp., Dept. D-10 
43 West 61 st Street, New York, N.Y. 10023 

n Please send mc Schober Organ Catalog and 
free 7-Inch "sample* 1 record, 

□ Enclosed please find $LOQ for 12-inch L.P. 
record of Schober Organ music. 



NAME 



I 
I 
I 



ADDRESS 
CITY 



STATE. 



-ZIP. 



■■ 
I 
I 
I 
1 
1 
I 
I 
I 
■ 
I 
I 
I 
1 
I 
I 



AMERICAN CRYSTAL CO. 

1623 Central Ave, Kansas City, Kan. 66102 Tel 913-342 5493 

Mfg, Crystals for most communication Equip, 
for use in; Small or ders accept ed Cryjtft| prfcgs % 0Q2% 

I W0WAY f| -J FUNDAMENTALS: 

SCANNERS ■— --" 

MONITORS 
TRANSMITTERS 
C.B. SYNTHESIZERS 
REPEATERS 

SCANNERS (Oper. 152,5 to 163,5 MHz„.0Q2% 
ELEMENT CRYSTALS .0005% 




2 to 14.9 MHz 
IS to 19.9 MHz 

THIRD MODE 
10 to 44.9 MHz 
45 to 55J MHz 



S5.25 
6 10 

5.35 
6.10 
5.00 






{channel freq, changed in customer's element) plus pig. & ins. 1 5.00 

C.8. {Class D Single channel. 1 to 23} ., . 2 75 

Amateur, HC6/U, + or - 1 KX., 32 pf . Fund 3,5 to 8.9 MHz \ \ \ \ 3^0 
Extras: Oven use Sh50,Submimature ,25* 093 pins JOrf 
Postage: 1/2 crystals 2 02s. each additional 1/2 crystals 1 oz. 
Write for quantity discounts 



you/ 






ASKED/. 
FOR 




HERE IT IS! . . . one complete U.S. Callback 

and one complete DX Callbook per year and no 
change in price. In addition you can keep your CALL- 
BOOKS up-to-date through a subscription to the new 
Service Edition Series published each March !, 
June 1 and September 1 — each one covering new 
licenses and all activity during the preceding quar- 
ter. Annual subscription to complete Winter CALL- 
BOOKS plus 3 Service Editions only $1435 postpaid 
for the U.S. and $11,45 postpaid for the DX. 



Over 265,000 QTHs 
in the U.S. edition 




Over 180,000 QTHs 
in the DX edition 



$ 6 



.& 



These valuable EXTRA features included in both editions! 
QSL Managers Around • Prefixes by Countries! 



the World! 

Census of Radio 
Amateurs throughout 
the world! 

Radio Amateurs' license 
Class! 

World Prefix Map! 

International Radio 

Amateur Prefixes 



Zips on all QTHs! 

A.R.R.L Phonetic 
Alphabet! 

Where To Buy! 

Great Circle Bearings! 

International Postal 
Information! 

Plus much more! 



See your favorite dealer or order direct {add 25£ for 
mailing in U.S., Possessions & Canada. Elsewhere add 
50$), 

50 YEARS OF SERVICE 
TO RADIO AMATEURS 

GET YOUR NEW ISSUE NOW! 



WRITE FOR 

mi 

BROCHURE! 



RADIO AMATEUR 

ca 



lib 



00 



k 



NC 



Oeot B 925 Sherwood Drive 
Lake Bluff. III. 60044 



94 



73 MAGAZINE 




Tome Bum Encode iu 



■ UP TO 5 FIXED 
TONES 

(factory set) 

■ ADJUSTABLE: 

— Duration 
— Output 

■ NO BATTERIES 

needed* 

■ FULLY ADAPT- 
ABLE 

■ EASY INSTALLA- 
TION 

■ CONTINUOUS 
TONE POSSIBLE 

■ FULL 1 YEAR RP 
WARRANTY 

Prices; MODEL TB-5 
5 lone (std) $37.50 

2 lone $32.50 

Special tones — Inquire 

(111, Residents, 
add 5% tax) 




FREE SPEC SHEETS 

NOW 

AVAILABLE 



r Electronics 

Box 1201 B 
CHAMPAIGN, ILL. 
61820 



Radio Amateur 
Emblems engraved 
with your call letters. 




□ Gofd 

□ Rhodium 

call letters 
$5.00 Ea, 



□ Gold 

□ Rhodium 

call letters 
$5.00 Ea. 



All illustrations 
are actual we. 




(D Gold 
n Rhodium 



call letters 
$5.00 Ea. 



Rush Order To: RADIO AMATEUR CALLB00K, Inc. 

Dept. E. 925 Sherwood Drive, Lake Bluff, III. 60044 




I 



I 



I 



HAM RADIO s?£« 



400 



\U> 



mc 




NPN HIGH POWER 
UHF TRANSISTORS 

2N3632 " w " 

BRAND NEW! LINEAR IC AMPS 

Type Description 

Q 703 RF-IF, 14 hookups. TO-5 . . 
Q 709C Operational Amp ■ ** - 

7 IOC Differential Amp*** 

□ 7 11C Memory, Sense, Amp*** + 
] 723A Voltage Regulator (DIP) . 

\2 TVR-20OO Hi -power 723 (DIP> 
D 741C Frecj. Comp. 709*** . , . . 
3 748C Freq. Adjustable 741***. 
~1 709-709 Dual 709 f s (DIP) . .. 

□ 741-741 Dual 741 f s (DIP) 
D 749-749 Stereo Preamp (DIP) . 



Hale 


Sale 


$1.19 


3 for 


S3. 00 


.59 


2 for 


1.00 


.59 


2 for 


1.00 


.59 


2 for 


l.OO 


1.49 


3 for 


3.75 


1-59 


3 for 


3.95 


.95 


3 for 


2.50 


.93 


3 for 


2.50 


1.49 


3 for 


4.00 


1.98 


3 for 


5.50 


1,98 


3 for 


5.50 



# # * 



Slate i*it T 2nd choice, Dual En Line, TO-5, 



FAIRCHILD IC SALE 



75C 3 for 52.00 
• Factory GUARANTEED* 

Q 914 Duol 2 In. Gate 
923 JK Flip Flop 




Phase Locked Ljoop 



NATIONAL 

3 LM565 

t A.®* W 



LIGHT EMITTING DIODES 



Use as logtc readouts, either on panel 
or fight on cards, Infinite Jife. 



$ 1 ^ 



*•' 



VARACTOR DIODES 

a 5 for $1— Ot»— 

Variable tuner capacitance 
diodes, For lOO's 61 tuning 
circuits. Kit includes; B- 
10pf, 10-20pf ( 20*30pf, 
3O-40pf, 40-5f)pf. 



2,5 AMR 
SILICON RECT 

Li 4 for $i 

• EPOXY 

• Microminiature 

• Obsolete* "bullet*" 







GIANT SALE ON NEW TTL 
TEXAS & NATIONAL ICs 



Buy Any 3 



Take 10% Discount! 



* Factory Tested! * Factory Guaranteed! 



Type 

D SH7400N 

SN7401N 

SN7402N 

L SN7404N 

D SN7405N 

3 SN7410N 

□ SN7420N 

D SN7430N 

D 5N7440N 

SN7441N 

D SN744GN 

5N7447N 

3 SN7472N 

SN7473N 

SN7474N 

SN7475N 

5N7476N 

SN7481N 

SN7483N 

SN7490N 

SN7491N 

5N7492N 

SN7493N 

SN7494N 

SN7495N 



□ 

LJ 

□ 

n 



Function 

Quad 2 input NAND sate 
5N7400 with open collect 
Quad 2 input NOR gate . . 
Hex inverter ...♦....., 
Hex inverter, open collect 
Triple 3 input NAND gate 
Dual 4 input NAND Kate 

8 input N%ND gate 

Dual 4 input NAND buffer 
BCD to-Decimal driver . . 
BCD-to-7 seg. dec. /driver 
BCD-to-7 seg. dec. /driver 
J-K Master slave flip-flop 
Dual J-K Master slave flip* 
Dual D triggered flip flop 
Quad bistable latch . . . . . 
SN7473, >*ith presef-n-Clear 
16- bit memory {scratch pad) 
4-bit binary full adder .... 
Decade counter ,.,.,... 
8-bit shift register , 

Divide by 12 counter 

4-bit binary counter ...... 

4 -bit Shift register , . , . 

4-bit register right N- left 



■ t -m P- "f 




flop 






.45 
.45 
.45 

-45 

,45 

.45 

.45 

1.50 

2.25 

2.25 

.69 

.88 

.69 

1.50 

.88 

ISO 

2.25 

1.98 

1.50 
ISO 
1.50 
1.50 
1.50 



D 15$ CATALOG on Fiber Optics, MCs\ Semi's, Parts 

Teritis: add postage. Hated: net 30, Cpd's 25%, 
Phone Orders: Wakefield, Mas« t C617) 245-3S29 
Ret-sMi 211 Albion St., Wakefield, Muaa. 



POLY PAKS 



P.O BOX 942 A 
Lynnfield, Mass. 

01940 



-.'_„_ J 



JANUARY 1972 



95 






READER SERVICE 

Please either tear out this list of advertisers and send 
it in to 73 with as many boxes checked off as you 
would like to see brochures, data sheets or cata- 
logs . . , or else make a copy and send that in. Do NOT 
fail to send for data on those products and services that 
interest you. Your magazine will be as large as the 
number of ads allow it to be ... so the more you 
encourage the advertisers the bigger magazine you will 
have. When you send for information, the advertisers get 
encouraged. Send. 



I 



PROPAGATION CHART 

J. H. Nelson 

Good (Open), Fair (O), Poor (X) 



January 1972 

SUN MON TUES WED THUR FRI 



SAT 



2 3 



9 W 11 

16 17 18 




ADVERTISER INDEX January, 1972 






I 23 24 25 % % 28 29 



I 

D Adirondack 28 E Mini-Products 15 ■ 
D American Xtal 94 D Motorola Cover IV 
a An-Tek 89 ° Nu Sigma Alpha 91 


30 31 






















EASTERN UNITED STATES TO: 


GMT: 00 02 04 06 08 10 12 14 16 18 20 I 


D Arnold's 91 ° Palomar 28 I 


ALASKA 


rt 


J 


7 


tt 


iVM 


3A 


|A 


3A 


7 


« 


21 1 


Q ATV 88 n Park Elea 93 I 


ARGENTINA 


14 


r 


7 


7 


7 


7 


14 


21 


21 


71 


21 2 


o Callbook 94 D Payne Radio 89 I 
O Circuit Specs. 76 D Pearce Simpson 89 | 
O Comcraft 20 D Poly Paks 95 


AUSTRALIA 


T4A 


76 


7B 


7B 


7 


7 


7 


78 


14 


14 


14 


CANAL ZONE 


14 


J 


7 


2 


7 


? 


7A 




z* 


21 2 


ENGLAND 


2 


1 


7 


3A 3A 


?? 


14 


21 


a 


14 


78 


HAWAII 


14A 


78 


7 


7 


7 


7 


7 


7 


76 


14A 


21 2 


P Comm. Spec. 90 D Rim Systems 88 I 


INDIA 


7 


7 


7B 


38 


36 


22 


7 


t4 


78 


78 


7 


O Cornell 88 n Robot Cover II 1 


JAPAN 


14 


78 


79 


7 


7 


7 


7 


7 


TO 


78 


76 


a Data Engineering 91 ° R P 95 . 
D Derrick Elec. 89 D Schober 94 I 


MEXICO 


14 


? 


7 


7 


7 


7 


7 


14 


21 


21 


21 " 


PHILIPPINES 


14 


76 


76 


76 


76 


7 


7 


7 


78 


76 


7B 


PUERTO RICO 


7 


7 


7 


7 


7 


3A 


7 


14 


14 


21 


21 


D Dy Comm 43 n Selectronics 80 [ 


SOUTH AFRICA 


7 


7 


7 


7 


76 


78 


14A 


21 


21 


21 


21 


D Dynalab 91 D Sentry 72 i 
□ Epsilon 89 D Simpson 78 


U. S. S. R. 


7 


3A 


3A 


3A 


3A 


78 


)Q 


14 


7A 


/M 


78 


WEST COAST 


14 


7 


7 


7 


7 


7 


3A 


7 


14A 


21 


21 i 


D E.S, Enterprises 76 a Slep 93 | 
D Estes 71 D Sonar 92 | 
□ Fair 90 D Standard 16 


CENTRAL UNITED STATES TO 


ALASKA 


1* 


t 


7 


3A 


3A 


3A 


3A 


3IA 


r | 14 


2T 


ARGENTINA 


14 


7A 


7 


7 


7 


7 


7 


14 


71 


21 


21 

— 


O Freck 90 D Tab Books 38 


AUSTRALIA 


21 


14 


76 


7B 


7 


7 


7 


78 


14 


14 


14 


n Gateway 86 D Telrex 34 i 
n J.J. Glass 65 a Tensor 33 
a Goodheart 93 a Vanguard 22 
D Hal 90,91 D Vibroplex 88 


CANAL ZONE 


14 


7 


7 


7 


7 


7 


7 


14A 


21 


21 


21 


ENGLAND 


78 


7 


7 


3A 


3A 


3A 


78 


14 


14 


14 


78 


HAWAII 


21 


14 


7 


7 


7 


7 


7 


7 


7 


I4A 


21 


INDIA 


7 


7 


7B 


36 


38 


38 


78 


7 


7 


78 


78* 


JAPAN 


14 


76 


76 


7 


7 


7 


7 


7 


7 


76 


78 


n Hairy 22 D Wolf 88 


MEXICO 


14 


7 


7 


7 


7 


7 


3A 


7 


14 


14 


14A 


O Henry Cover III a World QSL 88 | 
a H & L 91 | 
D Janel 89 73 Stuff j 
Q Jan Xtals 60 Reptr. Circ. Manual 44 ■ 
D Jefftronics 86 Ad Ad 56 1 


PHILIPPINES 


14 


7B 


TB 


76 


76 


7 


7 


7 


7 


78 


7B 


PUEHTOFUCO 


14 


7 


7 


7 


7 


7 


7 


14 


21 


si 


21 


SOUTH AFRICA 


14B 


7 


7 


7 


76 


76 


76 


14A 


21 


21 


21 


U. S. S. P. 


7 


7 


3A 


3A 


3A 


38 


»[ 7A 


7A 


78 


78 


WESTERN UNITED STATES TQ 


n Juge 70 TV 1 Book 64 1 


ALASKA 


14 


7a| 7 


a 


3 


3 


3 


3 


7 


7A 14 


D Lee Electronics 42 Subscriptions 82, 83 

D Linear Systems 81 Radio Bookshop 84 

° Mann 66 Repeater Atlas 92 | 


ARGENTINA 


21 


14 


7 


7 


7 


7 


7 


14 


21 


21 


21 


AUSTRALIA 


21 


21 


14 


76 


7 


7 


7 


7 


76 


14 


14 


CANAL ZONE 


14 


7A 


7 


7 


7 


7 


7 


14 


21 


21 


21 


ENGLAND 


76 


7 


7 


3A 


3A 


3A 


36 


7B 


14 


14 


7Q 


I 


HAWAII 


21 


21 


14 


7 


7 


7 


7 


7 


7 


14A 


21 A 
76 


I 


INDIA 


7B 


14 


76 


3fl 


36 


36 


7 


7 


; 


7 


| 


JAPAN 


21 


14 


76 


7 


7 


7 


7 


7 


7 


7 


70 


I 


MEXICO 


14 


14 


7 


7 


7 


7 


7 


7 


14 


21 


21 


PHILIPPINES 


21 


14 


7B 


76 


76 


7 


7 


7 


7 


7 


78 


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A - Next higher frequency may be useful also 
B = Difficult circuit this period* 


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73 MAGAZ 




THE MOST EXCITING RECEIVER AND TRANSCEIVER TO ENTER THE AMATEUR SCENE IN RECENT YEARS. THE 
KENWOOD R-599 SOLID STATE RECEIVER AND T-599 HYBRID TRANSMITTER HAVE ESTABLISHED NEW STAN- 
DARDS OF PERFORMANCE, RELIABILITY, FLEXIBILITY, STYLING AND VALUE. 

THE R-599 RECEIVER: „5 microvolt sensitivity 
(amateur bands 1.8-21.0 MHz) • Dial readout 
to y 2 kilocycle • Special detectors for SSB, AM, 
and FM • Transceive operation with T-599 • 
Built-in 100 kc and 25 kc crystal calibrator * 
Built-in 500 cycle CW filter • Provision for two 
meter and six meter coverage with optional ac- 
cessory self -contained converters • Advanced 
"Space-Age 1 ' styling • Adjustable threshold 
squelch « The price . . . only $329.00* 



E T-599 TRANSMITTER: Clear, stable, select- 
able side-band, AM and CW • 4-way VFO Flex- 
ibility plus Receiver Incremental Tuning (RIT) 
when used with the R-599 • Amplified ALC • 
Built-in VOX • Full metering, including cathode 
current, plate voltage, ALC and relative Power 
Output • Built-in CW Sidetone monitor and semi- 
automatic break- in CW * Built-in power supply • 
Maximum TVI protection • Employs only 3 vac- 
uum tubes • The price ... only $365.00* 



THE KENWOOD 

TS-511S 

TRANSCEIVER 

The Kenwood TS-511S is a 
five band SSB and CW trans- 
ceiver packed with power 
and performance . , • offering 
features never before avail- 
able in its price range. For 
example: built-in VOX, crys- 
tal calibrator, noise blanker 
receiver incremental tuning, 
1 kHz frequency readout, 8 
pole filter, stable FET VFO, 
dual conversion and acces- 
sory CW filter* 




FREQUENCY RANGE: 10, 15, 20, 
40 & 80 meters (Amateur Bands) 
Q MODES: LSB, USB, CW □ 
INPUT POWER: 500 watts PEP, 
300 watts CW nominal. □ 
SENSITIVITY: 3.5-21,6 mHz band 
0.5 uv S/N 10 db 28.0-29,7 mHz 
band; 1-5 uv S/N 10 db and less 
than 100 cps frequency drift per 
30 minutes after warm-up D 
SELECTIVITY: SSB more than 2.4 



KC (at 6 db) with 2 to 1 slope ratio 
CW more than 0.5 KC (at 6 db) D 
A*F. OUTPUT: more than 1 
watt (10% distortion) D TUBE& 

SOLID STATE COMPONENTS: 10 

Tubes, 1 IC, 37 Transistors, 4 FET, 

52 Diodes D PRICE: $398.00* 
ACCESSORIES: Power Supply with 

built-in speaker $105.00* External 

VFO $99*Q0f CW Filter $35.00* 

* Prices subject to import surcharge 



1 1240 W. Olympic Blvd., Los Angeles, Calif. 90064 213/477-6701 
931 N. Euclid, Anaheim, Calif. 92801 714/772-9200 

Butler, Missouri 64730 816/679-3127 



/ 



/ 








When you spin this knob, how far are you from 



selectivity ? 



« ■ ■ m ■■ ■ sj Mechanical tuning condensers — 

Sl3l© OT til© 31*1 however bulky — cant give it to you. 

Our new Tuning Diodes 
(Voltage Variable Capitance Diodes) can. a With 
Q's up to 3000 these semiconductor devices 
offer the absolute ultimate in selectivity and sensitivity for tuning, 
AFC, and general frequency control, □ If you're rigging new, you also 
get tremendous space-saving advantages. About three of our Tuning 
Diodes this size ^^ replace the bulkiest mechanical condenser. □ With 
all that, these mm diodes should probably be quite expensive. 
but they aren't // Suggested Ham Net: $1.10 each, In six capacities 
from 6.1 to // 110 pf, At your authorized HEP Supplier now. a Also 
there now: // our Balanced Modulator/Demodulator IC, C6050G — 
the HEP '/ replacement for the much publicized MC1496G (also 
MC1596G when used within rated temperature specs). Suggested 
Ham Net: $3.35. 

Happy soldering. 




/WOT"OF?OL A HEP* Semiconductors 

P.O. Box 20924, Phoenix, Arizona 85001